Chocolate and Rats
From the Jan/Feb 1996 Rat & Mouse Gazette
Working as a veterinary technician in a practice that has numerous rat and mouse owners as clients I am often asked if chocolate is toxic to their pets. My initial reaction was to apply the same guidelines we use for dogs to murines (rats and mice), but then became curious if there were any actual studies doneon these species which would give specifics. First, it is important to understand what is toxic about chocolate in species that are susceptible to chocolate poisoning. It is the theobromine in chocolate which in large amounts has diuretic effects, relaxes smooth muscles, and stimulates the heart and central nervous system. Caffeine has a greater effect on the central nervous system and is also found in small amounts in chocolate. Pharmacologically, theobromine is included in a group of naturally occurring methylxanthine alkaloids along with caffeine, theophylline, and the synthetics, aminophylline and etamiphylline. Relative to other methylxanthines, theobromine is pharmacologically weak. Theobromine, as well as other drugs mentioned do have therapeutic effects when given at the proper dosage and are used in the treatment of respiratory diseases and heart disease. I have treated my own rat with aminophylline (dose prescribed by my veterinarian) when in the final stages of Mycoplasmosis. This is a bronchial dilator and did offer her some relief. I had a necropsy done atWashington State University and they found no side effects from the aminophylline treatment. Theobromine is found in higher concentration in unsweetened baker's chocolate (15mg/g) than in milk chocolate (1.5 mg/g). White chocolate is low enough in both theobromine and caffeine and would be unlikely to cause poisoning.
I began my search for published information pertaining to rats and chocolate toxicity with my professor Ken Tudor D.V.M. at the college where I am enrolled in the Veterinary Technician program. He contacted his associate Jean Hoffman A.H.T. who specializes and teaches classes on laboratory animals. Neither were able to find any reference material for me on the subject, but suggested I call Dr. Kean at the Laboratory Animal Facility at Loma Linda University. I contacted Dr. Kean, but he also knew of no particular studies conducted on chocolate toxicity in rats. I then began searching my college library and a database at Cal. Poly. Pomona, but I could find no research articles specifically dealing with chocolate and rats, only chocolate toxicity in dogs, so I called a friend who is a veterinarian in Washington, Dr. Wada, with connections to the Veterinary program at Washington State University. She nor her associates at W.S.U. knew of any published information either. I also had the veterinarian I work for and another local veterinarian, Dr. Castiglione, help with the research and both were unable to find any information pertaining to rats, again only dogs. I even put my question on the bulletinboard for veterinarians on America On-Line and received a response from Dr. Brown, who also could not give any specific level, but did say that chocolate can be toxic in large amounts.
I now resorted to opinions from all the above mentioned sources and none wouldstate that a small quantity of milk chocolate would be toxic to a rat. All agreed that they could see no harm in feeding a small quantity of chocolate as a treat along with a balanced and nutritionally complete diet. They did feel that chocolate had no nutritional value and that a less sugary treat would be more beneficial to the rats' diet. Dr. Brown wrote "you would be better off not giving it at all rather than worrying about exactly how much is toxic." Dr. Castiglione specifically suggested not feeding any baker's chocolate, or products such as homemade chocolate cake or frosting made with large quantities of baker's chocolate. I would assume that rats would not even want pure baker's chocolate as it is not sweet and even has an unpleasant flavor. Dr. Kean said that he could see no problem in giving a couple of semi-sweet chocolate chips, even on a daily basis, as long as the rat was receiving a nutritionally complete diet and the treat did not replace this diet. Most were fearful that if they were to tell a client that it is okay to give chocolate as an occasional treat the client would overfeed the treats when they see how much their pets enjoy it. Their shared opinion was that unlike dogs, rats usually do not eat as voraciously and would be much less likely to ingest a toxic quantity of chocolate, even if offered, if they had other nutritional food. The best guideline any could give me is the levels which may cause symptoms to be exhibited by a dog which is about .04 oz (1.3 mg) baker's chocolate or 0.4 oz(13mg) milk chocolate per kilogram (2.2 pounds) of body weight, and doses 10 times higher may be lethal. In simpler terms, this equates to a 5 pound dog needing to consume about a half square of baker's chocolate, or 5 oz. (4 avg. candy bars) to be dangerous.
I was disappointed to find no published facts on this subject and to realize that this concept that chocolate is toxic to rats is based on the fact that in large quantities it is toxic to dogs and feel that most veterinarians are more knowledgeable about canine care and therefore, often apply the same principles to rats. I feel they are also playing it safe by telling clients not to feed chocolate due to the fear that if they give it the okay, a client will give their rat too much and offset the nutritional balance of the diet. I have been active in training and showing dogs for 24 years and was always told to "never feed my dog chocolate." It was not until I began working in the veterinary field and became educated on the actual levels of chocolate ingestion which are toxic that I realized that even if my 27 pound Sheltie stole a couple of piecesof See's candy off the table he wasn't going to die.
My conclusion is that an occasional, small piece of chocolate is certainly not going to kill my rats and I know they really enjoy it. Chocolate has no nutritional value for me either, but I hope no one denies me my Almond Joy! I think the important aspect is for the owner to use common sense when giving this treat, just as in feeding your rats in general. They must be given a complete, nutritious diet. I feel you have a higher likelihood of losing your pet to Mycoplasmosis, or to tumors than to chocolate toxicity.


Minimal Parathyroid Surgery
The Minimally Invasive Technique Utilizing Intraoperative Nuclear Mapping
Also called: Minimally Invasive Radioguided Parathyroidectomy, or "MIRP" The technique of minimally invasive parathyroidectomy using intraoperative nuclear mapping (also called minimally invasive radioguided parathyroidectomy (MIRP)) was pioneered in
Also called: Minimally Invasive Radioguided Parathyroidectomy, or "MIRP"
The technique of minimally invasive parathyroidectomy using intraoperative nuclear mapping (also called minimally invasive radioguided parathyroidectomy (MIRP)) was pioneered in 1993-95 at the University of South Florida by Dr. James Norman, M.D. During the past several years, the MIRP procedure has clearly become the preferred method of removing parathyroid tumors. More than 120 scientific articles have been published by more than a dozen US universities during this time showing that the MIRP has a higher success rate and lower complication rate than standard parathyroid surgery. This minimal parathyroid surgical technique has gained wide acceptance as the most advanced, least invasive, and preferred method for operating on parathyroids.
The concept of minimally invasive radioguided surgery is simple: about 97% of patients with parathyroid disease have just one bad parathyroid...so give them a very small operation to remove just that one bad gland and leave the other 3 alone. In other words, change the big standard operation into something very small, fast, simple, and much less complicated for the vast majority of patients. The best news is that the cure rates reported to date for the MIRP procedure are as high or even higher than they would be if the more extensive and complicated operation was performed. This operation is possible because of the small probe shown in the picture. This probe will detect minute levels of radioactivity and so the surgeon uses it during the operation to find the hyperactive parathyroid tumor which is very easily made radioactive for about 4 hours with a very small (and very safe) dose of a special drug.
There are numerous potential advantages to minimally invasive radioguided parathyroidectomy. First of all, the surgeon has a very good idea which one of the four parathyroid glands is hyperactive prior to beginning the operation. This allows the surgeon to operate on one very small area of the neck rather than exposing the entire neck and both sides of the thyroid. If the operation only takes place on one side of the neck, then the risks of damaging nerves and other important structures on the other side of the neck are eliminated and, therefore, the risks of this procedure are expected to be less than half of that seen during a complete neck exploration (all reports of MIRPs in the medical literature have shown a lower complication rate). If you are contemplating parathyroid surgery, ask your doctors about this procedure, you will be glad you did.
Another advantage of the MIRP technique is that it is almost always performed without general anesthesia (put to sleep). The operation is typically performed through a 2.5cm (1 inch) incision (shown in yellow) rather than the usual 14 cm (6 to 10 inch) incision (shown in red). The surgeon is able to complete the operation through this smaller incision because he/she does not have to search for all four parathyroids to find the one which is overactive. Since the diseased gland is radioactive, the probe is placed into the wound every few minutes to direct the dissection right to where it is hiding. The probe also allows the adenoma to be removed in much less time. DON'T LET YOUR DOCTOR DO THE OLD FASHIONED OPERATION. THE RESULTS ARE NOT AS GOOD, AND THE COMPLICATION RATE IS MUCH HIGHER! KEEP READING!
The average operative time to remove the diseased parathyroid gland using this technique is about 17 minutes as compared to an operation which can take up to three hours (or more!) when it involves exploration of both sides of the neck. Some centers (such as the Norman Parathyroid Clinic) are now reporting that as many as 75% of operations can be performed in under 15 minutes. The ability to do the procedure this quickly means that minimal anesthesia is needed, and unnecessary dissection within the neck is avoided. Combined, these advantages allow almost all patients to be sent home within an hour or two of the operation rather than spending one or two days in the hospital. Most institutions which are performing this type of surgery send virtually all patients home following this procedure (UPDATE: June 2005, Dr. Norman has reported sending 100% of his last 2,000 parathyroid patients home within 2 hours). Even patients over 80 years old have had this procedure and sent home within an hour or two. The small wound heals quickly and only very rarely do patients need any prescription pain medications. Reported cure rates for this minimal approach are 99 percent, but most expect a long term cure rate of about 98 to 99 percent (Dr. Norman's reported and published cure rate is 99.75% -- remember, the standard operation has a cure rate of about 86 to 95%).
Advantages of Minimally Invasive Radioguided Parathyroidectomy (The MIRP Procedure)
- Local anesthesia or a very light general anesthesia using IV sedation (twilight anesthesia) -- instead of general anesthesia where a breathing tube is put down the throat..
- 3/4 to 1.25 inch incision instead of 4 to 8 inch incision (thin people can expect a 1 inch or even smaller incision).
- Usually less than 30 minutes in the operating room vs. 2 to 5 hours. (average operating time is under 18 minutes)
- No risk to nerves and other structures on the "normal" side of the neck (risk to the voice-box nerve should be less than 1/4 of the risk if performed by the old "exploration").
- Less than 1/4 of the potential complications than the standard operation.
- Much smaller overall operation so less pain (only Tylenol or aspirin needed).
- Return to normal activities usually by the next day (instead of a week or so of recuperation time). Nearly zero recuperation time needed.
- Usually home in an hour or 2 (vs. 1 to 3 days in the hospital).
- Most patients go out to eat the evening of surgery.
- Significantly less expensive than the standard operation. *
- Cure rate significantly higher than the standard operation.
- Dramatically reduced chance of surgery not helping the problem.
- Zero risk of hypoparathyroidism (a rare complication seen when all parathyroids are removed)
* Eight publications in medical journals have now shown that the cost of performing a MIRP is significantly less than the standard operation; as much as 1/3 the overall cost! The most recent one (Journal of Head and Neck Cancer, November 2003) shows it can be about 1/2 the cost of the old fashioned operation)
Who is a Candidate for Minimally Invasive Parathyroidectomy?
This new approach to parathyroid surgery has taken the surgical and endocrinology specialties by storm. The cure rate is significantly higher than any other parathyroid operation and the complication rate is near zero (significantly less than 1 percent when performed by expert parathyroid surgeons). This is changing the way all doctors look at this disease. Since hyperparathyroidism can now be fixed easily for the vast majority of patients in less than 20 minutes, most endocrinologists are sending all of their patients for this minimal operation. They feel it is riskier to wait around and potentially develop osteoporosis or kidney stones than it is to have this procedure. Besides, the operation makes the majority of people feel better and enjoy life more!
This technique is revolutionizing the way parathyroid surgery is performed. More and more surgeons are being trained in radioguided surgery for breast cancer and malignant melanoma, as well as parathyroids and so radioguided surgery is becoming much more common. The results of this minimal approach has now been proven to be BETTER than the gold standard operation and they are embracing it fully. A recent study of endocrinologists has shown that this minimal parathyroid operation is the preferred method to remove parathyroid tumors. View an abstract of the opinions of nearly 800 endocrinologists surveyed regarding MIRP (click here). * 96% of endocrinologists would travel to another state to have a MIRP by an expert if they needed a parathyroid operation!
Virtually all patients with hyperparathyroidism can have a Mini-Parathyroid operation (MIRP) when performed by one of the few extremely experienced parathyroid surgeons in the world. Those patients in whom a high quality Sestamibi scan shows a single adenoma as the cause for the primary hyperparathyroidism are extremely good candidates for minimally invasive parathyroidectomy, and their operations should be expected to last about 15 - 25 minutes.. About 85 - 90 % of all patients with primary hyperparathyroidism will localize in this manner and can have this very fast out-patient procedure. The other ~ 10 - 15 % will not localize on their Sestamibi (a "negative Sestamibi Scan) and will likely need all four parathyroid glands examined, however, with radioguided techniques (MIRP), this can still be done in under 25 minutes in almost all patients, through the same 1 inch incision. YES, ALL PATIENTS CAN AND SHOULD HAVE A MINI- PARATHYROID OPERATION. YES, ALL PATIENTS, REGARDLESS OF THEIR SESTAMIBI SCAN RESULTS CAN HAVE A MINI OPERATION IF THEIR SURGEON KNOWS HOW TO DO IT ! You may be better served by finding an expert. As you will read on other pages of this website, there is no other operation that is more dependent upon the experience of the surgeon. Parathyroid surgery is all about experience, so shop for your surgeon very smartly!
Read what patients say about having a MIRP mini-parathyroid operation. These are patients just like you who never heard of a parathyroid gland until they got this disease. They don't know anybody else who has had this disease, and their doctor doesn't see to much of it either. Read about patients who have had their entire problem cured in 30 minutes or less! CLICK HERE.
Has This Technique Been Published?
This is a frequently asked question, and it should be! Physicians have long believed that new medical procedures / drugs should be studied scientifically and subjected to critical review by other physicians and experts in the field. The answer to this question is YES. So as not to clutter up this page, we put this information on another publication page.
We are often asked "If this is the best way to do parathyroid surgery, then why doesn't every surgeon do it this way?" Well, there are several reasons: Since this is a rare disease and most surgeons see only one case of parathyroid disease every year or two it doesn't make economic sense for the hospital to purchase the equipment.. Typically, the radioguided probe will cost $150,000 and this is simply too much if it is to be used only once or twice per year. Secondly, the surgeon is required to take a training course to use radioguided techniques in the operating room. These courses are expensive, and require the surgeon to miss 2 days of work. Again, it is not economically sound for a surgeon to do this if he/she only sees 1 or 2 patients per year with this disease. Finally, the surgeon has to take courses and yearly updates on using radioactive materials. This can be a big pain in the rear! It all comes down to economics and experience. If the patients are not demanding radioguided surgery, and the surgeon / hospital are not performing more than a dozen or so parathyroid operations per year, then it doesn't make economic sense to perform radioguided parathyroid surgery.
The biggest reason that all surgeons don't do mini-parathyroid surgery, however, is because this is a rare disease. It is un-real to expect every surgeon to be an expert for a rare disease. In fact, if you think there is a parathyroid expert in every large city, you are wrong. There cannot be an expert in every city for a rare disease. Every surgeon gets to do 0 to 2 parathyroid operations per year... hardly enough practice to be an expert. Why do they do it then??? Because it is a tricky operation it pays very well. Your general surgeon won't say no to you... there is too much money involved.


Lisbon lies along the northern banks of the River Tagus (Rio Tejo) and the slow flowing water of the river helped create Lisbon the city that it is today. The protection that the estuary offered from the ferocious Atlantic attracted the early settlers which developed into a major Roman port. Later the Age of Discover, regarded as the golden age of Portugal, originated from the docks of the Rio Tejo and the wealth of the colonies flowed back along the Tagus River to fund the extravagance of the era. The Portuguese as a nation are travellers with communities dotted throughout the world and this characteristic can be traced back to the close connection with the seas and the rivers of which the Tejo is the most important.
The River Tagus flows into the Lisbon region from the north of Portugal and opens into a wide but shallow estuary that boarders Lisbon to the east. The estuary flows out into the Atlantic Ocean in a westerly direction between the high cliff headlands on the south bank and the flatter slopes of the capital.
At the narrowest point of the mouth of the Tagus estuary the Ponte de 25th Abril suspension bridge connects the capital with the southern commuter distracts of Almada. This bottle neck travelling south was alleviated by the Vasco da Gama Bridge which stretches out from eastern Lisbon for 17km to the western bank of the Rio Tejo estuary.
The Tagus River originates from central Spain (the Serra de Albarracín) and cuts a generally westerly course for 716 km (445 miles) until the Portuguese boarder. The Tagus slows significantly close to the boarder and meanders southwards forming the frontier between Spain and Portugal for 47 km (29 miles). The final 275 km (171 miles) is within Portugal where it provides a constant water supply for farm irrigation to an otherwise arid region.
The total length of the Rio Tejo is 1,038 km (645 miles) and is the third longest river of the Iberian Peninsula behind Douro and the Ebro Rivers but the Tejo drains the second largest basin of the peninsula at 80,100 square kilometres (30,927 square miles).


The ICMAB presents activities around "Women in Science" at #YoMoBCN20
In 2020, the ICMAB will be present at the next edition of YoMo "Youth Mobile" conference (25-29 Feb 2020) with two activities around women in science: the dramatised reading "Madame Châtelet and her Instagram followers", which visibilized women scientists of our history, and the talk "The hidden truth: Women behing the periodic table", which talks about the different periodic table elements that have been discovered by women and some curiosity around women and the chemical elements. Both activities will take place on Thursday, 27 February 2020 at La Farga de l'Hospitalet.
Come and discover the women scientists of all times!
Do you know many women scientists? Surely there are many around you! Come and see this play to discover some of the most wise scientists in history. You will discover some of their discoveries and we are sure you will learn new things! In addition, their creators and performers are also women scientists!
How many women do you see in the periodic table?
Science has not made it easy for women, and this is also true in the case of the periodic table. However, there are some elements that have been discovered by women, or with their important implication. We'll talk a little bit about that to learn more about our scientific past.
- YoMo: The interactive, hands-on festival of science and technology that brings classroom learning to life.
- When: 25 – 29 February 2020
- Where: La Farga de L’Hospitalet, Barcelona


Why Lessons From The Kerner Commission Continue To Resonate
Fifty years ago this summer, race riots broke out in a number of American inner cities. In the aftermath, President Lyndon Johnson appointed a commission to determine the causes. It was called the Kerner Commission and its report provided a startling and controversial conclusion: “Our nation is moving towards two societies, one black, one white — separate and unequal.”
Last year, Lester Graham (@MichiganWatch) from Here & Now contributor Michigan Radio told us why the Kerner Commission’s recommendations were ignored, and why in an age of Black Lives Matter the report’s lessons still resonate.
Copyright 2021 NPR. To see more, visit https://www.npr.org.


Exploring The Last Green Valley: Ravens more than symbol of Halloween
Exploring The Last Green Valley: Ravens more than symbol of Halloween
On the pallid bust of Pallas just above my chamber door;
And his eyes have all the seeming of a demon’s that is dreaming,
And the lamp-light o’er him streaming throws his shadow on the floor;
And my soul from out that shadow that lies floating on the floor
Shall be lifted- nevermore!
— From “The Raven” by Edgar Allen Poe
It’s almost Halloween, the perfect opportunity to share information on the fascinating and somewhat scary raven. The common raven (Corvus corax) is alive and well here in The Last Green Valley.
When I visit West Thompson Lake and Recreation Area, I frequently see a pair of ravens. I’ll see them flying over the water and large fields or roosting on top of the nearby church or dam gatehouse.
I spoke with Cathy St. Andre, the Corps of Engineers’ park ranger, about the ravens.
“We believe the ravens have been nesting here every year since 2008,” she said. “This year, they nested on the west side of the cliff and we had five of them all summer long here. I am not sure if they have dispersed for the fall and winter, but we have at least two resident ravens all year long every year. They love hanging out on the roof of the gatehouse.”
I also frequently see ravens when hiking Mount Monadnock in southern New Hampshire. I hear fascinating vocalizations of squawks and croaks as I make my way up the trail and through the tree line.
Breaking into the open and approaching the summit, I always see one or more ravens flying with acrobatic twists and turns in the mountain winds. My guess is they nest along the rocky summit.
I often speak to them when I first hear their calls and usually ask permission to hike their mountain. Thankfully they have never denied me admittance to their Monadnock realm.
There are excellent sources of information about the common raven. My go-to online resource for information about birds is, “All About Birds” by the Cornell Lab of Ornithology. You can find it at allaboutbirds.org. Here are some facts about ravens from the website:
- The common raven is not just large but massive, with a thick neck, shaggy throat feathers and a Bowie knife of a beak. In flight, ravens have long, wedge-shaped tails. They’re more slender than crows, with longer, narrower wings, and longer, thinner “fingers” at the wingtips. They are entirely black, right down to their legs, eyes and beaks.
- Ravens aren’t as social as crows; you tend to see them alone or in pairs except at food sources like landfills. They are confident, inquisitive birds that strut around or occasionally bound forward with light, two-footed hops. In flight they are buoyant and graceful, interspersing soaring, gliding and slow flaps.
- Ravens live in open and forest habitats across western and northern North America. This includes deciduous and evergreen forests up to tree line, as well as high desert, sea coast, sagebrush, tundra and grasslands. They do well around people, particularly rural settlements, but also some towns and cities.
- Ravens are acrobatic fliers, often doing rolls and somersaults in the air. Young birds are fond of playing games with sticks, repeatedly dropping them then diving to catch them in midair.
- Breeding pairs of ravens hold territories and try to exclude all other ravens throughout the year. In winter, young ravens finding a carcass will call other ravens to the prize. They apparently do this to overwhelm the local territory’s owners by force of numbers to gain access to the food.
- People the world over sense a certain kind of personality in ravens. Edgar Allan Poe clearly found them a little creepy. The captive ravens at the Tower of London are beloved and perhaps a little feared; legend has it that if they ever leave the tower, the British Empire will crumble. Native people of the Pacific Northwest regard the raven as an incurable trickster, bringing fire to people by stealing it from the sun, and stealing salmon only to drop them in rivers all over the world.
- Ravens can mimic the calls of other bird species. When raised in captivity, they can even imitate human words.
- Ravens will eat almost anything they can get hold of. They eat small animals from mice and baby tortoises up to adult rock pigeons and nestling great blue herons, eggs, grasshoppers, beetles, scorpions and other arthropods, fish, wolf and sled-dog dung, grains, buds, berries, pet food, carrion and many types of human food, including unattended picnic items and garbage.
- Ravens build their nests on cliffs, in trees and on structures such as power line towers, telephone poles, billboards and bridges. Cliff nests are usually under a rock overhang. Tree nests tend to be in a crotch high in the tree, but below the canopy and typically farther down in a tree than a crow’s nest would be.
- The common raven population increased across the continent between 1966 and 2014, according to the North American Breeding Bird Survey. “Partners in Flight” estimates their global breeding population to be 20 million with 18 percent living in Canada, 9 percent in the U.S. and 3 percent in Mexico.
- Ravens tend to do well around people, profiting from the garbage, crops, irrigation and roadkill that accompany us. Their numbers are generally stable or rising in western North America. As eastern forests were cut down in the 19th and early 20th centuries, ravens disappeared from most of eastern North America, but they are returning to the Northeast as forest cover regenerates.
One of my favorite nature writers is Bernd Heinrich, professor emeritus of biology at the University of Vermont.
He is the leading authority on ravens, and if you’re interested in learning more about this amazing and very special bird, I suggest Heinrich’s books, “Mind of the Raven: Investigations and Adventures with Wolf-Birds” and “Ravens in Winter.”
His research into ravens is all-encompassing and includes raising ravens from hatchlings to adults as well as countless hours observing them in the wild.
His exhaustive study, fieldwork and analysis help to answer his question in the preface to “Mind of the Raven”: “All animals solve the age-old problems related to food, partnerships, sex, shelter, home, and caring for their young. Yet ravens have throughout history commonly been singled out to be most like man. Why? What is special about ravens that invite such a comparison?”
After reading Heinrich’s books and learning more about ravens, I’ll make sure to be on the lookout for them when next I climb Monadnock or visit West Thompson Lake.
Poe may have found them to be creepy but clearly Corvus corax is so much more than a symbol of Halloween.
Our region is full of fascinating wildlife as well as beautiful and diverse natural resources. I hope you’ll take the time to learn, appreciate, and help to protect the habitat our animals need to thrive and survive here in The Last Green Valley.
Bill Reid is chief ranger of The Last Green Valley National Heritage Corridor and has lived in the region for more than 30 years. He can be reached at email@example.com.
The Norwich Bulletin is granted first serial rights and associated electronic rights to publish the preceding article. The Last Green Valley, Inc. retains all other rights to the work.
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Action: Provide supplementary food for songbirds to increase reproductive success
Key messagesRead our guidance on Key messages before continuing
- Two studies from the USA found evidence for higher population densities of magpies and American blackbirds in areas provided with supplementary food, whilst two studies from the UK and Canada found that population densities did not appear to be affected by feeding.
- Twelve studies from across the world found that breeding productivity was higher for fed birds than controls. The increases were through higher hatching or fledging rates, or higher chick survival or recruitment rates. One study from the USA found that these increases were only found in dry years.
- Eleven studies from Europe and the USA found that fed birds had no higher, or even lower breeding productivity or chick survival than control birds.
- Nine studies from Europe and North America found that the eggs of fed birds were larger or heavier, or that the chicks of fed birds were in better physical condition: being larger, heavier, faster growing, more symmetrical or having a better immune response. In one study this was only true in a heavily polluted site. However, eight studies from across the world found no evidence for better condition or increased size in the eggs or chicks of fed birds.
- Six studies from across the world found that food-supplemented pairs laid larger clutches than unfed birds, whilst 14 studies from Europe and North America found that fed birds did not lay larger clutches, or even laid smaller ones.
- Fifteen studies from across the world found that birds supplied with supplementary food began nesting or laying earlier than controls, although in two studies this was only true for young females or in one of two habitats. In one study, a high fat, high protein diet had a greater effect on laying date than a high fat, low protein diet. One study found that fed birds had shorter incubations than controls whilst another found that fed birds re-nested quicker than controls and had shorter second incubations.
- Four studies from the USA and Europe found that fed birds did not lay any earlier than controls.
- Seven studies from across the world found that fed parent birds showed positive behavioural responses to feeding, such as being more likely to re-nest, less likely to be parasitized or showing better anti-predator responses, spending more time incubating or building larger nests.
- Three studies from across the world found neutral or negative responses to feeding, including being more likely to be invaded by conspecifics, making no more breeding attempts or showing no preference for fed nest boxes compared to controls.
Supporting evidence from individual studies
A controlled cross-over study in southern Sweden in 1972-3 (Källander 1974) found that great tits Parus major nesting in an 8 ha (1972) or 6 ha (1973) area of oak-hazel woodland supplied with supplementary food began laying eggs significantly earlier than great tits in an adjacent 16 ha or 18 ha control (unfed) area. The difference was significant irrespective of whether all females, one year-old females or older females were examined (average laying date of 1st-5th May for 44 nests in fed areas vs. 6th-11th May for 75 control pairs). Supplementary food consisted of 32 or 33 trays positioned throughout the wood and provided daily with 20-35 g of mealworms from 11th-27th April 1972 and between 10th April and 14th May 1973. On average there were 2 trays/territory in 1972 and 1.5 trays/territory in 1973. The authors note that other species including wood nuthatches Sitta europea and chaffinches Fringilla coelebs also took food from the trays.
A replicated and controlled study in mixed farmland in north-east Scotland between 1971 and 1973 (Yom-Tov 1974) found that carrion crow Corvus corone nestlings in nests provided with supplementary food had significantly higher hatching, survival and fledging rates than those in control (unfed) nests (with human ‘predation’ included: 79% of 11 fed nests hatching at least one chick, 71% of ten having at least one chick surviving for ten days and 71% fledging at least one chick vs. 61% of 28, 54% of 15 and 43% of 12 for controls). Nestlings from fed nests, however, were no heavier than those from controls, when comparing first-hatched with first-hatched etc. Supplementary food consisted of one domestic hen’s egg and five dead hen chicks provided every day from when laying began and increasing to one egg and ten chicks from the seventh day after hatching until fledging. Other experiments in this study found that winter feeding (a hen’s egg and five chicks provided between January and April 1973) led to crows laying clutches earlier but did not affect clutch size (average laying date of April 13th and 4.4 eggs/clutch for ten fed territories vs. April 18th and 4.3 eggs/clutch for 21 controls). Further experiments examined the effect of moving supplementary food further from nests, but the author argues that these results are confounded by supplementary food being taken by non-target birds. Finally, additional experiments in the study found that crow nesting density did not increase following the provision of supplementary food and additional nesting sites in breeding territories, discussed in ‘Provide artificial nesting sites’.
A controlled trial in coniferous forest in southwest Sweden in 1976-7 (von Brömssen & Jansson 1980), found that willow tits Parus montanus and crested tits P. cristatus in a 1.8 km2 area provided with supplementary food started laying eggs significantly earlier than individuals in a 5.5 km2 control (non-supplemented) area (willow tits: average of 2-5 days earlier, 44 pairs tested; crested tits: average 5-8 days earlier, 38 tested). There was no corresponding difference in 1978, when no food was provided. Twelve-day old crested tit nestlings were significantly heavier in the fed area (average of 12.2 g for fed area vs. 11.5 g for control, number of chicks not provided) but there was no difference in willow tit nestlings (average of 10.6 g for fed area vs. 10.7 for control, number of chicks not provided). Clutch sizes did not differ between areas for either species (willow tits: average of 8.1-8.2 eggs/clutch for fed area vs. 7.7-8.2 for controls; crested tits: average of 5.3-5.4 eggs/clutch for fed area vs. 5.0-5.2 for controls). Food was provided at feeding stations located in the approximate centre of each fed territory and contained one feeder of sunflower seeds and three coconut shells containing a mixture of tallow, soy protein, wheat germ, sun-flower seeds, vitamins and minerals. In 1976 feeding started on 20th February and in 1977 on the 20-24th March, in both years it continued until all females had started laying and resumed for the first half of June (when second clutches could be expected to be laid).
A replicated cross-over study in a pine forest site in southern Sweden in 1974-5 (Hogstedt 1981) found that female black-billed magpies Pica pica laid earlier, had larger clutches and laid larger eggs when supplied with supplementary food compared to when no food was provided (average of 3.5 days earlier, an extra 0.56 eggs/clutch and eggs weighing 0.33 g more, ten females studied). Fed pairs were less likely to lose nestlings and had higher fledging success than control (unfed) pairs (88% of 20 fed nests having one surviving nestling and 2.7 fledglings/breeding attempt vs. 48% and 1.3 fledglings/breeding attempt for 32 controls). Supplementary food consisted of 300 g of fish provided in the centre of experimental territories every other day from 15th March until eggs hatched, when it was raised to 600 g. This represents approximately 75% of a pair’s daily requirement before hatching and 65-150% after hatching. Food was also provided in seven territories without magpies, but did not attract any new pairs.
A replicated, controlled experiment on marshlands sites in Washington state, USA, in the springs of 1977-8 (Ewald & Rohwer 1982), found that red-winged blackbirds Agelaius phoeniceus from territories supplied with supplementary food laid eggs significantly earlier than blackbirds from control (unfed) territories (1977: 17 days earlier in eight territories where feeding began on 31st March, 12 days earlier in five territories fed from 5th April; 1978: 26 days earlier). However, in 1978 clutch size was significantly lower in fed territories (3.4 eggs/clutch, 122 fed clutches vs. 3.6 eggs/clutch for 126 controls), the authors suggest this is due to early-laid clutches being smaller – if clutches laid before April 10th were excluded then clutches were not significantly smaller. Fed territories provided with supplementary food also had higher rates of chick mortality than control territories (numbers not provided) and were invaded by non-territorial red-winged and yellow-headed blackbirds Xanthocephalus xanthocephalus at significantly higher rates than controls in 1978 (4.9 intruders/ha in 33 fed territories vs. 1.1/ha for 54 controls), but not in 1977, or when feeder density was reduced in 1978 (0.8 intruders/ha for 17 fed territories vs. 1.3 intruders/ha for 19 controls). Supplementary food consisted of sunflower seeds, cracked corn and puppy food on 30 cm square trays. In 1977 one tray was placed in each of 13 territories on two marshes (controls were on five other marshes); in 1978, trays were placed on a 6 m grid on a single marsh, a tray density approximately ten times that in 1977, reduced to one feeder in each territory several weeks after females arrived.
A small study from January-March in 1979-1980 in Utah, USA (Reese & Kadlec 1984), found that juvenile black-billed magpies Pica pica that established nest sites closer to supplemental food stations experienced higher rates of nestling starvation than nests further away. Very few adult magpies visited food stations. Dominant juvenile males, however, established nests significantly closer to food stations. Of seven nests within 100 m of food stations, six experienced nestling starvation while only one farther than 100 m did. Supplementary feeding did not enhance clutch (6.4 and 6.4 eggs/nest) or brood (5.0 and 4.8 nestlings / nest) size between nests closer to food stations (16 nests) and those further away (13 nests). Similarly, mean clutch initiation was not significantly different between treatments. The authors point out that supplementary feeding can serve as a proximate stimulus to commence nesting on sites that are not inherently of good quality. Food stations were provisioned with beef bones or black-tailed jack rabbit Lepus californicus carcasses.
A replicated and controlled study on Mandarte Island, British Colombia, Canada (Arcese & Smith 1988), found that song sparrows Melospiza melodia provided with supplementary food in 1985 laid earlier, had larger clutches than control (unfed) birds, were more likely to re-nest following breeding failures and were less likely to be parasitized by brown-headed cowbirds Molothrus ater (average laying date of 10th April, 3.3 eggs/clutch, 2.8 breeding attempts and 18% of nests parasitized for 15 fed pairs vs. 28th April, 2.8 eggs/clutch, 2.2 breeding attempts and 45% for 34 controls). This led to fed females raising approximately 3.8 young/female to independence compared to 1.0 young/female for controls. However, eggs and nestlings from fed birds were no larger than those from controls nor more likely to hatch or survive to independence (averages of 3.1 g/egg, 16.8 g/nestling at six days old, 78% hatching success and 83% survival to independence vs. 3.0 g/egg, 15.6g, 73% and 70%) and young from fed territories did not have enhanced reproduction (8.6% of 58 fed young reproducing vs. 12.5% for 40 controls). Supplementary food consisted of dog food, vitamins, mealworms Tenerbrio sp. and millet seed provided continuously in feeders in the centre of each territory from five weeks before laying started (28th February) until the last young had left the nest (24th July). The authors note that 1985 was a year of peak song sparrow density. This study also described the impact of feeding on adult survival, discussed in ‘Provide supplementary food to increase adult survival’.
A controlled before-and-after study in Washington, USA, in March-June 1979-82 (Knight 1988), found that twice as many black-billed magpies Pica pica nested, and that they began laying significantly earlier, in a 0.3 ha area of willow Salix spp. in 1981 when a dead bullock was cut open to locally increase invertebrate numbers, compared to 1979-80 and 1982 when there was no bullock present (eight nests in 1981, average laying date if 24th March vs. three or four nests and a laying date of 2nd-4th April in other years). There were no corresponding changes in two areas that were not supplied with a carcass (six and nine nests and 1st-6th April for all years studied). There were no differences in clutch size or the number of young fledged from nests with the carcass present. The bullock weighed approximately 450 kg and died between 1st and 7th March 1981 and attracted large numbers of blow flies (Calliphoridae), most of which had left by the 22nd March.
A replicated, paired site study in 1984-1985 in 17 experimental and 17 control pairs of blue tit Parus caeruleus nests in Lund, Sweden (Nilsson & Smith 1988), found that blue tit pairs that were artificially provisioned with food exhibited significantly greater reproductive success. Supplementary feeding significantly shortened the length of the incubation period. The probability that an egg would hatch was higher in provisioned nests than in control nests (98 and 90% of 198 and 199 eggs respectively). However, nestling survival up to 13 days did not differ between the pairs. Each pair was selected so that the last egg in both clutches was laid on the same date and the pairs nested in similar habitats. Four days after the last egg was laid, a container with 7 g of mealworms was placed into the experimental nest, while an empty container was placed into the control nest. Age and wing length did not differ between dyad pairs.
A randomised, replicated and controlled experiment around two lakes in Washington state, USA, in 1981 (Wimberger 1988), found that red-winged blackbirds Agelaius phoeniceus from territories supplied with supplementary food laid eggs 8-13 days earlier than blackbirds from control (unfed) territories, for first, second, third and fourth nests of the year (20 territories studied). Each lake was divided in half, with one half provided with sunflower seeds from the 4th April. The average number of females in each territory was increased by feeding on one lake (average of 9.0 females/territory on fed territories vs. 6.5 females/territory on controls, eight territories studied) but not the other (average of 5.2 females/territory on fed territories vs. 4.7 females/territory on controls, 12 studied).
A cross-over study in a coppiced oak forest in southern France in 1986-7 (Clamens & Isenmann 1989) found that blue tit Parus caeruleus and great tit P. major pairs in an area provided with supplementary food started laying clutches significantly earlier than pairs in a control (unfed) area (1986: 9 pairs in a 10 ha fed area laid six days earlier than 26 pairs in a 50 ha control area; 1987: 15 pairs in a 30 ha fed area laid five days earlier than 18 pairs in a 30 ha control area). However there were no significant differences in clutch size or the number of young hatched between treatments (average of 9.2 eggs/clutch for 24 fed clutchea vs. 8.3-9.1 eggs/clutch for 44 controls) and, in 1987, significantly fewer chicks fledged from blue tit nests in fed areas than control areas (average of 3.0 chicks/nest for 11 fed pairs vs. 6.3 chicks/nest for 15 controls). There was no significant difference in productivity in 1986 (7.1 chicks/nest for seven from fed areas vs. 7.3 chicks/nest for 23 controls). The authors suggest this could be due to fed clutches hatching before the peak in natural food in 1987.
A study in Alberta, Canada, between 1986 and 1988 (Dhind & Boag 1990) found that black-billed magpies Pica pica that used supplementary food provided in a single feeder in an urban area laid eggs 6-7 days earlier than magpies that did not use the feeder (seven pairs used the feeder in 1987, six in 1988; 22 pairs did not use the feeder in 1987, 11 in 1988). Nestlings from parents that used feeders were heavier and had higher survival and fledging rates than those from parents that didn’t use the feeder, (fed nests: average weight of 184 g, ten nests, 71% survival of seven through a snow storm in 1987, 4.1-4.5 nestlings fledged/nest for 13 nests; unfed nests: 163-168 g for 13, 15% survival of 20, 1.1-1.8 nestlings fledged/nest for 31) although there were no differences in clutch size or breeding density (fed nests: 7.4-7.8 eggs/clutch for ten clutches, 126-134 m between 13 nests; unfed nests: 6.8-6.9 eggs/clutch of 23, 134-153 m between 57 nests). Supplementary food consisted of approximately 1 kg of dog food pellets provided each week from August 1986 until June 1988.
A randomised, replicated and controlled paired study in a Sonoran desert site in Arizona, USA, in the breeding seasons of 1986 and 1987 (Simons & Martin 1990) found that 28 cactus wren Campylorhynchus brunneicapillus broods were 10.5-20.0 g heavier from territories provided with supplementary food, compared with control broods. Parents from fed territories were also more likely to have second clutches than controls (12 of 14 fed pairs attempted second broods vs. seven of 14 control pairs). Fed nestlings were also larger and had higher post-fledging survival rates in 1986 but not 1987 (1986: 14 pairs, linear measurements 1.0-2.7 mm larger than controls, 15 fed fledglings surviving for four to six weeks after fledging vs. seven control fledglings; 1987: 14 pairs, linear measurements 0.2-0.6 mm larger than controls, 19 fed fledglings surviving vs. 16 controls). The authors suggest that differences between years were due to higher levels of natural food occurring in 1987. Supplementary food consisted of 35 g of mealworm Tenebrio molitor larvae and noctuid moth caterpillars supplied every other day from one or two days after hatching until nestlings fledged (approximately 20 days later) and comprised 75% (1986) and 80% (1987) of food delivered to nests.
A small randomised and controlled paired study in parkland and mixed woodland in southern Scotland in spring and summer 1990 (Johnston 1993) found that great tit Parus major nestlings in eight artificially enlarged broods were no larger at 15 days old when provided with supplementary food, compared to nestlings from seven control (enlarged but not fed) broods. Broods were enlarged by the addition of three nestlings (added after hatching). Supplementary food consisted of an average of 2.2 g of minced meat and nutritional supplements fed twice daily to half the experimental brood on days six through 12 after hatching. This represents most of a nestling’s daily energetic requirements. This study also investigated the impact on the condition of provisioning females, discussed in ‘Provide supplementary food to increase adult survival’.
A replicated and controlled study in grasslands in southern Sweden between 1982 and 1990 (Källander & Karlsson 1993) found that common starlings Sturnes vulgaris supplied with supplementary food began laying significantly earlier than controls (first laying date of 21st April-5th May for fed nests vs. 22nd April-10th May). There were no such differences between nests in the years when supplementary food was not supplied. However there were only occasional differences in egg weight, no differences in clutch size or nestlings weights and fledging rates were actually lower in fed nests in 1990 (4.3 young/nest for fed nests vs. 5.6 for controls). Supplementary food consisted of approximately 100g of mealworms placed in small feeders either on the outside or inside of nest boxes, supplied to different colonies in 1982 and 1985 and a subset of nests at a third colony in 1990. Feeding began approximately one month before laying started and stopped once all females began laying. Feeding represented more than the daily energetic needs of a pair of starlings.
A replicated, controlled and paired study in a mixed forest in the central Netherlands in 1987 (Verhulst 1994) found that pied flycatcher Ficedula hypoleuca chicks from pairs provided with supplementary food were significantly more likely to be recruited into the local breeding population than chicks from control (unfed) pairs (7.9% of nestlings from 12 fed clutches recaptured as breeding adults vs. 1.1% from 15 controls). However, fed pairs did not start laying earlier, produce larger clutches, hatch more young, hatch young earlier than control pairs (13 fed pairs started laying on May 18th, average of 6.3 eggs/clutch, 5.5 chicks/clutch and a hatching date of June 6th vs. May 19th, 6.2 eggs/clutch, hatching 5.4 chicks/clutch and June 6th for 16 controls), probably due to the paired nature of the study. In addition, there were no differences between treatments in terms of nestling growth, survival, tarsus length or weight (5.5 chicks/clutch fledging, average weight of 13.9 g, average tarsus length of 17.4 cm for 12 fed pairs vs. 5.5 chicks/clutch fledging, average weight of 13.8 g, average tarsus length of 17.2 cm for 15 controls). Supplementary food consisted of mealworms provided in excess beginning two days after chicks hatched. This study also examines the impact of feeding on adult survival, discussed in ‘Provide supplementary food to increase adult survival’.
A replicated and controlled study in alpine meadows and pine woodlands on Honshu, Japan, in May-September 1986-9 (Nakamura 1995) found that one year-old alpine accentor Prunella collaris females in territories provided with supplementary food began laying clutches significantly earlier than those in control territories (first egg laid on average on 25th-29th June for fed 16 one year-old females vs. 5th-13th July for 17 control one year-olds). There was no such difference in older females (first egg laid on average on 17th-19th June for 18 fed females vs. 21st-23rd June for 19 controls). There were no differences in duration of the copulation period, the number of breeding attempts or the timing of settlement in territories for either one year-old or older females. Supplementary food consisted of 300 g of millet and canary seed provided two to three times a week beginning in May and continuing until September.
A small, controlled before-and-after study on Frégate Island, Seychelles, in 1989-90 (Komdeur 1996), found that Seychelles robins Copsychus sechellarum had significantly higher reproductive success in 1990 when provided with supplementary food, compared to in 1989, when food was not provided (2.0 nestlings/pair and 1.4 independent young/pair in 1990 vs. 0.8 nestlings/pair and 0.2 young/pair in 1989). There was no corresponding change in four control (unfed) territories. Food consisted of 20–25 freshly killed cockroaches, grated coconuts, boiled rice and fish provided twice a week, and an area of 4 m² of soil was broken up in an attempt to facilitate access to natural prey (e.g. worms and beetle larvae). Increases were apparently due to earlier laying dates, more time incubating and nest guarding, higher hatching and provisioning rates, higher chick fledging weight and higher levels of parental care.
A replicated and controlled trial in a dune and scrubland system in Florida, USA, in 1993 (Schosch 1996), found that female Florida scrub jays Aphelocoma coerulescens in ten groups provided with supplementary food initiated clutches significantly earlier (on average 16 days earlier) than females from 32 control (unfed) groups. There was no significant difference in clutch sizes between treatments. Non-breeders from fed groups were no less likely to become breeders than those from control groups (fed groups: five of 23 non-breeders established territories; controls: four of 23). Feeding consisted of providing dried dog food, peanuts and mealworms were provided twice daily at feeding stations in the middle of the territories from late January until females finished laying. Food was provided ‘in excess’. This study also reported on the effects on adult condition, discussed in ‘Provide supplementary food to increase adult survival’.
A replicated and controlled before-and-after trial in scrubland, gullies and caves in southern Spain in 1980-3 (Soler & Soler 1996) found that European jackdaws Corvus monedula laid earlier, laid more eggs and had higher breeding success when given supplementary food, compared to either the same colonies in previous years, or to control colonies (average laying date of 25th April, 6.0 eggs/clutch and 48% of all eggs fledging for 13 fed nests vs. 27th April, 5.4 eggs/clutch and 20% of all eggs fledgingfor 18 experimental colonies in previous years vs. vs. 27th April, 5.4 eggs/clutch and 29% of all eggs fledging for 18 control colonies). Starvation rates were also lower in fed colonies (2.5 nestlings/nest starving in 12 fed nests vs. 3.4 nestlings/nest in 12 controls). Predation rates were lower in fed colonies (0% of 20 fed nests predated vs. 22% of 27 control nests) and the authors argue that this was due to better group defence in fed colonies due to higher breeding densities, although nesting densities were only significantly higher in one colony, comparing 1983 and 1982, other comparisons were non-significant (colony A when not fed: 56%, 63% and 56% of nests occupied in 1980-2 vs. 88% in 1983 when fed; colony B: when not fed: 50%, 67% and 33% of nests occupied in 1980-2 vs. 100% in 1983). Supplementary food consisted of four hens’ eggs for each jackdaw pair supplied twice a week and 4-7 kg of bread, continuously supplied.
A randomised, replicated and controlled trial in a forest in Illinois, USA, in 1998 (Styrsky et al. 2000), found that ‘early-season’ house wren Troglodytes aedon nestlings (i.e. from clutches laid in mid-May) in nest boxes provided with supplementary food were significantly heavier than nestlings from early-season control broods (fed nestlings approximately 2% heavier than controls, 62 tested). There was no difference in weight between fed and control late-season (laid in late June to early July) broods (53 tested). There were no differences between treatments for tarsus lengths, growth rates or survival until fledgling for either early or late season broods. Food consisted of 30 g of mealworms Tenebrio molitor supplied each day within the nest boxes.
A replicated, controlled trial on an island in Lake Rotorua, North Island, New Zealand, between September 1995 and February 2001 (Castro et al. 2003), found that stitchbirds (hihis) Notiomystis cincta in territories provided with supplementary food laid significantly more eggs and had higher fledging and recruitment success than control (unsupplemented) birds (average of 4.4 eggs/clutch for 17 fed nests vs. 3.9 eggs/clutch for 18 controls; 70% fledging success for 22 fed nests vs. 32% for 14 controls and 35% recruitment success for 16 fed nests vs. 13% for 13 controls). In addition, fed females began laying second clutches significantly sooner than controls and incubated second clutches for significantly less time (15.2 days of incubation for eight fed clutches, and a 4.0 day interval before four second clutches vs. 16.8 days incubation for eight controls and a 13.3 day interval for six). There were no significant differences in hatching success or the incubation period of first clutches, between fed and control birds. Supplementary food consisted of either commercial honeyeater food (provided every day) or a solution of sugar or jam (provided every third day) in hummingbird feeders. Territories were considered ‘fed’ if nests were within 50 m of a feeder. The authors suggest that population viability on Mokoia Island may be dependent on supplementary food.
A randomised, replicated and controlled study in a 10 ha Australian reed Phragmites australis wetland in southern Australia, over two breeding seasons (September to January) in 1999-2001 (Eikenaar et al. 2003), found that Australian reed warbler Acrocephalus australis females provided with supplementary food spent longer incubating eggs than control (unfed) females (12 fed females spent approximately 57% of time incubating vs. 51% for ten controls). There was also a significant difference between days when food was provided and those when it was not (on fed days, 59% of time spent incubating vs. 52% of time on unfed days, seven tested). There were no differences between other measures of incubation attendance, such as start and end times of incubation bouts or the average length of bouts. However, broods from fed territories had larger hatching asynchronies (calculated as the difference in size, at one to three days old, between the first- and last-hatched chicks, divided by the mean size of all nestlings) than control pairs (tarsus length asynchrony of approximately 0.15 and weight asynchrony of approximately 0.35 for ten fed broods vs. 0.10 and 0.20 for 19 controls). The effect of feeding on fitness of chicks or parents was not reported. Supplementary food consisted of 30 g of blowfly maggots (over 150% of daily energetic requirements of an adult reed warbler) provided every other day whilst eggs were incubated, but stopped before eggs hatched.
A randomised, replicated and controlled paired study in mixed deciduous forests in the Netherlands in 1999 (Grieco 2003), found that blue tit Parus caeruleus nestlings from eleven nest boxes provided with supplementary food had more even leg lengths than nestlings from eleven control (unfed) nest boxes. There were no differences in leg size between treatments and no data were provided on survival or reproductive success. Supplementary food consisted of mealworm Tenerbio molitor and wax moth Galleria mellonella larvae placed inside the nest boxes and making up one third of the nestlings’ total food. Food was provided from day of hatching until the chicks fledged.
A continuation of Reynolds et al. 2003 in 2001 and 2002 (Reynolds et al. 2003) found that Florida scrub jay Aphelocoma coerulescens chicks from second and third-laid eggs had significantly higher fledging rates from territories provided with high-fat, high-protein supplements compared to those from controls in 2001 but not 2002 (2001: 100% of eleven 2nd and 3rd-hatched chicks fledged from fed nests vs. 53% of seventeen 2nd-hatched and 40% of ten third-hatched chicks from controls; 2002: 63% of eight 2nd-hatched and 71% of seven 3rd-hatched vs. 81% of 16 and 60% of ten for controls). In addition, more third-hatched chicks survived to independence in fed territories in 2001 (50% of four vs. 0% of ten) but not 2002 (43% of seven vs. 30% of ten). Fed chicks also grew flight feathers significantly faster, but there were no other differences in growth (body mass and leg length) or survival between the groups.
A randomised, replicated and controlled cross-over trial in a dune and scrubland system in Florida, USA, in 2000 and 2001 (Reynolds et al. 2003), found that that 21 female Florida scrub jays Aphelocoma coerulescens provided with high-fat, low-protein (HFLP) supplementary food and 21 females provided with high-fat, high-protein (HFHP) food laid significantly larger clutches than 55 control females in 2000 but not 2001 (2000: approximately 3.7 eggs/clutch for HFLP diets, 3.2 eggs/clutch for HFHP and 2.8 eggs/clutch for controls; 2001: 2.7 eggs/clutch, 3.1 eggs/clutch and 2.8 eggs/clutch respectively). This was due to earlier laying, discussed below. Clutches on the HFHP diet had a tendency to have larger third-laid eggs, but other eggs were not significantly different in size between treatments. Feeding began in early- or mid-January and continued until females began laying, usually six to eight weeks later. Food consisted of food pellets containing 19.3% fat and with a protein content of either 3.5% or 34.5%.
A replicated and controlled paired site study from March-August in 2000-2003 in 20 paired nest box groups (10 placed along wetland edges and 10 in farmlands) in Rutland, England (Field & Anderson 2004) found that tree sparrows Passer montanus showed no preference for nest boxes supplied with supplementary food (four fed boxes colonised vs. four unfed). There was no difference in the number of nesting attempts made by birds with or without supplementary food although the mean clutch size was significantly higher in nests closer to supplementary food (5.6 compared to 5.0 eggs / clutch). The authors point out that the small spatial scale of the study (1 km between pairs) may have confounded any effect of supplementary feeding. Nest box groups consisted of 5 nest boxes placed 2-20 m apart; sunflower seeds were randomly provided to one nest box group within each pair.
A replicated, controlled trial in mixed agricultural habitats in southern Spain (De Neve et al. 2004) found that, when provided with supplementary food, male black-billed magpies Pica pica built significantly larger nests than controls (average of 5.1 units for 39 nests in fed territories vs. 4.6 units for 123 nests in controls) and females laid significantly larger eggs (average egg volume of 10.0 cm3 for 36 fed clutches vs. 9.5 cm3 for 119 controls). However there were no significant differences between groups in terms of laying date or clutch size (average of 25th April for 46 fed clutches vs. 12th April for 162 controls; 6.9 eggs/clutch for 38 fed clutches vs. 6.8 for 128 controls). Supplementary food consisted of 150 g dog food mixed with bread and water supplied every two days from before nest-building began until after the end of the breeding season.
A randomised, replicated and controlled trial at a prairie site in Kansas, USA, in April-August 1997 (Pearse et al. 2004) found that female Bewick’s wrens Thyromanes bewickii and house wrens Troglodytes aedon from nest boxes provided with supplementary food spent longer incubating than females from control (unfed) nest boxes (Bewick’s wrens: average incubation bout of 52 min and 82% of time spent on the nest for seven fed females vs. 35 min and 70% for eight controls ; house wrens: averages of 30 min and 81% for nine fed females vs. 13 min and 71% for eight controls). There were no differences in date of clutch initiation, clutch size, the average length of time spent away from the nest or hatching success between treatments (Bewick’s wrens: average bout away from the nest of 10 min for seven fed females, hatching success of 78% vs. 13 min and 74% for eight controls; house wrens: average of 5 min and 96% for nine fed females vs. 5 min and 82% for eight controls). Supplementary food consisted of 15 g of mealworm Tenebrio molitor larvae supplied inside nest boxes every day during incubation, equivalent to almost twice a female wren’s daily energetic requirements.
A continuation of (Schoech et al. 2004) between 2000 and 2003 (30), found that breeding groups of Florida scrub jays Aphelocoma coerulescens provided with high-fat, low-protein (HFLP, provided in 2000-2 only) supplementary food started laying eggs significantly earlier than control (unfed) territories, whilst territories provided with high-fat, high-protein (HFHP) food laid significantly earlier still (first laying on average of approximately day 16th March for 50 HFHP territories vs. March 20th for 29 HFLP territories vs. March 28th for 115 controls).
A replicated, controlled experiment in Arusha National Park, Tanzania, in October and November 1995 and 1996 (Scheuerlein & Gwinner 2006), found that East African stonechat Saxicola axillaris (formerly S. torquata axillaris) chicks from ten pairs provided with supplementary food did not grow any faster between hatching and seven days old than chicks from 15 control (unfed) pairs. However, feeding appeared to reduce the impact of common fiscals Lanius collaris, a predator of stonechats, the presence of which reduced growth rates in chicks from control pairs (n = 7), but not fed pairs (n = 5). Supplementary food consisted of 30 g of mealworms Tenebrio molitor provided every day, from approximately a month before laying began.
A replicated, controlled trial in habitats in southern Spain in 2001 (De Neve et al. 2007), found that black-billed magpie Pica pica nestlings provided with supplementary food had significantly higher cell-mediated immune responses (CMI, the change in swelling around insect bites, a measure of immunocompetence) in arid scrub, but not in irrigated farmland and woodland (arid scrub: average CMI of approximately 1.18 mm for fed nestlings vs. 0.85 m for controls; irrigated farmland/woodland: average CMI of 1.20 mm for fed nestlings vs. 1.18 mm for controls; 58 nests studied). In addition, fed nestlings showed significantly lower levels of the ectoparasite Carnus haemapterus (Diptera: Carnidae), but only in arid habitats (arid scrub: average infestation intensity of 0.40 arbitrary units for fed nestlings vs. 0.90 arbitrary units for controls; irrigated farmland/woodland: average 1.60 arbitrary units for fed nestlings vs. 1.65 arbitrary units for controls; 28 nests). Feeding had no effect on chick growth, weight or on the prevalence of blood parasites. Supplementary feeding consisted of 0.1 ml of high-calorie, nutrient-rich paste provided every other day for a total of 14 days.
A controlled, replicated study on San Clemente Island, California, USA, between 2000 and 2006 (Heath et al. 2008) found that pairs of San Clemente loggerhead shrikes Lanius ludovicianus mearnsi in territories provided with supplementary food and with rodent control during April-July produced, on average, 2.5 more fledglings each year (55 breeding attempts), compared to control pairs (62 attempts), and 1.4 more fledglings each year compared to territories with rodent control but no feeding (55 attempts). In drier-than-average years, fed pairs also raised more fledglings to independence (40 days old) than other pairs (1.8 more fledglings than control pairs, 0.7 more than rodent control only pairs). There was no effect in wetter-than-average years. Management in December-March did not increase either measure of productivity. This study also investigated the impact of just rodent control, which is discussed in ‘Control predators on islands’ and the success of captive-bred individuals, in ‘Release captive-bred individuals’.
A replicated and controlled study in a range of oak forest habitats on Corsica, France, in the springs of 2006 and 2007 (Bourgault et al. 2009) found that blue tits Parus caeruleus (also known as Cyanistes caeruleus) provided with supplementary food began laying eggs significantly earlier in a holm oak Quercus ilex dominated site (females from 30 fed pairs began to lay approximately seven days earlier than controls), but not in two broad-leaved oak Q. humilis dominated sites or a second holm oak site. The authors suggest that this difference is due to broad-leaved oak forests having up to ten times more food for blue tits than holm oak forests. Clutch size did not differ between fed and control territories in any of the sites. Supplementary feeding comprised unlimited access to food in feeders within territories, beginning in mid-January and continuing until egg laying began.
A replicated and controlled study in open pine Pinus sylvestris forests in southwest Finland in 2005 (Eeva et al. 2009) provided 87 great tit Parus major nestlings with three supplementary diets: autumnal moth Epirrita autumnata larvae (high in carotenoids – chemicals needed for coloured feathers) and mealworms (diet 1); mealworms and water-dispersed lutein (an important carotenoid, diet 2); mealworms and distilled water (diet 3). Nestlings fed on diets 1 and 2 were larger and heavier than control (unfed) nestlings and nestlings fed on diet 3, but only in areas with high levels of heavy metal pollution (polluted areas: average wing length of approximately 46 mm and body mass of 16.5 g for diet 1 nestlings vs. 46 mm and 15.8 g for diet 2 vs. 44 mm and 15.0 g for diet 3 and 43 mm and 15.0 g for controls; unpolluted areas: 48 mm and 16.5 g for diet 1 vs. 46 mm and 16 g for diet 2 vs. 46 mm and 16.5 g for diet 3 vs. 47 mm and 17 g for controls). In addition, diet 2 nestlings had higher blood lutein levels and correspondingly higher carotenoid chroma (a measure of colour intensity) in breast feathers than other diets and control chicks across both pollution levels (7.5-15.0 µg/ml blood lutein and 0.30-0.35 carotenoid chroma for diet 1 vs. 24.0-28.0 µg/ml and 0.41-0.45 for diet 2 vs. 7.5-16.0 µg/ml and 0.30-0.36 for diet 3 vs. 5.5-17.5 µg/ml and 0.30-0.36 for controls). Supplementary food did not have an effect on fledgling probability. One gram of food was provided every other day from the third day after hatching to the 13th, making approximately 20% of the required food in this time.
A randomised, replicated cross-over experiment in scrubland on South Island, New Zealand in austral spring 2000-1 (Barnett & Briskie 2010) found that on a day when they were provided with supplementary food, silvereyes Zosterops lateralis spent significantly longer incubating and had shorter periods away from the nest, compared to a day when they were not provided with food (adults on fed days spent approximately 94% of time incubating and periods off the nest averaged one minute vs. approximately 84% of time on nests and 3.5 minute periods off the nest, ten nests). However, feeding did not increase the length of individual incubation bouts, or the number of times parents left the nests each hour (longest incubation bouts averaged 39.6 mins when fed vs. 34.1 mins when unfed, ten nests; parents leaving nests an average of 2 times/min when fed vs. 2.3 times/min when unfed, seven nests). Supplementary food consisted of beef fat and sugar mixed and provided in pine cones on one of two experimental days and not provided on the other. No data is provided on the breeding success consequences of feeding.
A replicated, controlled study over 3 breeding seasons in 2006-2008 in 3 treatment blocks (2 experimental and 1 control; 96 nestboxes/block) of broadleaf, deciduous woodland in Worcestershire, UK (Harrison et al. 2010), found that blue tits Parus caeruleus (also known as Cyanistus caeruleus) and great tits Parus major began laying significantly earlier (by averages of two and three days respectively), had reduced clutch size (mean reduction: 0.4 and 0.7 eggs), shortened incubation periods (mean reduction: 0.9 and 0.7 days), lowered hatching success (in blue tits only: mean reduction: 1.4%) and reduced brood size (mean reduction: 0.6 and 0.5 chicks for blue and great tits respectively). Treatment blocks were separated by a 90 m buffer strip. In each year, one treatment block received no supplementary food and two treatment blocks received peanut cake (comprising 50% ground peanuts and 50% beef tallow). Treatments were rotated amongst plots.
- Källander H. (1974) Advancement of laying of great tits by the provision of food. Ibis, 116, 365-367
- Yom-Tov Y. (1974) The Effect of Food and Predation on Breeding Density and Success, Clutch Size and Laying Date of the Crow (Corvus corone L.). Journal of Animal Ecology, 43, 479-498
- von Brömssen A. & Jansson C. (1980) Effects of food addition to willow tit Parus montanus and crested tit P. cristatus at the time of breeding. Ornis Scandinavica, 11, 173-178
- Hogstedt G. (1981) Effect of Additional Food on Reproductive Success in the Magpie (Pica pica). Journal of Animal Ecology, 50, 219-229
- Ewald P.W. & Rohwer S. (1982) Effects of supplemental feeding on timing of breeding, clutch-size and polygyny in red-winged blackbirds Agelaius phoeniceus. Journal of Animal Ecology, 51, 429-450
- Reese K.P. & Kadlec J.A. (1984) Supplemental Feeding: Possible Negative Effects on Black-Billed Magpies. The Journal of Wildlife Management, 48, 608-610
- Arcese P. & Smith J.N.M. (1988) Effects of population density and supplemental food on reproduction in song sparrows. Journal of Animal Ecology, 57, 119-136
- Knight R.L. (1988) Effects of Supplemental Food on the Breeding Biology of the Black-Billed Magpie. The Condor, 90, 956-958
- Nilsson J. & Smith H.G. (1988) Incubation feeding as a male tactic for early hatching. Animal Behaviour, 36, 641-647
- Wimberger P.H. (1988) Food Supplement Effects on Breeding Time and Harem Size in the Red-Winged Blackbird (Agelaius phoeniceus). The Auk, 105, 799-802
- Clamens A. & Isenmann P. (1989) Effect of supplemental food on the breeding of blue and great tits in Mediterranean habitats. Ornis Scandinavica, 20, 36-42
- Dhind M.S. & Boag D.A. (1990) The effect of food supplementation on the reproductive success of black-billed magpies Pica pica. Ibis, 132, 595-602
- Simons L.S. & Martin T.E. (1990) Food Limitation of Avian Reproduction: An Experiment with the Cactus Wren. Ecology, 71, 869-876
- Johnston R.D. (1993) The effect of direct supplementary feeding of nestlings on weight loss in female Great Tits Parus major. Ibis, 135, 311-314
- Källander H. & Karlsson J. (1993) Supplemental Food and Laying Date in the European Starling. The Condor, 95, 1031-1034
- Verhulst S. (1994) Supplementary food in the nestling phase affects reproductive success in pied flycatchers (Ficedula hypoleuca). The Auk, 111, 714-716
- Nakamura M. (1995) Effects of supplemental feeding and female age on timing of breeding in the Alpine Accentor Prunella collaris. Ibis, 137, 56-63
- Komdeur J. (1996) Breeding of the Seychelles magpie robin Copsychus sechellarum and implications for its conservation. Ibis, 138, 485-498
- Schoech S.J (1996) The effect of supplemental food on body condition and the timing of reproduction in a cooperative breeder, the Florida scrub-jay. The Condor, 98, 234-244
- Soler M. & Soler J.J. (1996) Effects of experimental food provisioning on reproduction in the jackdaw Corvus monedula, a semi-colonial species. Ibis, 138, 377-383
- Styrsky J.D., Dobbs R.C. & Thompson C.F. (2000) Food-supplementation does not override the effect of egg mass on fitness-related traits of nestling house wrens. Journal of Animal Ecology, 69, 690-702
- Castro I., Brunton D.H., Mason K.M., Ebert B. & Griffiths R. (2003) Life history traits and food supplementation affect productivity in a translocated population of the endangered Hihi (stitchbird, Notiomystis cincta). Biological Conservation, 114, 271-280
- Eikenaar C., Berg M.L. & Komdeur J. (2003) Experimental evidence for the influence of food availability on incubation attendance and hatching asynchrony in the Australian reed warbler. Journal of Avian Biology, 34, 419-427
- Grieco F. (2003) Greater Food Availability Reduces Tarsus Asymmetry in Nestling Blue Tits. The Condor, 105, 599-603
- Reynolds S.J., Schoech S.J & Bowman R. (2003) Nutritional quality of prebreeding diet influences breeding performance of the Florida scrub-jay. Oecologia, 134, 308-316
- Reynolds S.J., Schoech S.J & Bowman R. (2003) Diet quality during pre-laying and nestling periods influences growth and survival of Florida scrub-jay (Aphelocoma coerulescens) chicks. Journal of Zoology, 261, 217-226
- Field R.H. & Anderson G.Q.A. (2004) Habitat use by breeding tree sparrows Passer montanus. Ibis, 146, 60-68
- De Neve L., Soler J.J., Soler M., PÃ©rez-Contreras T., MartÄ±n-Vivaldi M. & MartÄ±nez J.G. (2004) Effects of a food supplementation experiment on reproductive investment and a post-mating sexually selected trait in magpies Pica pica. Journal of Avian Biology, 35, 246-251
- Pearse A.T., Cavitt J.F. & Cully J.F. (2004) Effects of Food Supplementation on Female Nest Attentiveness and Incubation Mate Feeding in Two Sympatric Wren Species. The Wilson Bulletin, 116, 23-30
- Schoech S.J, Bowman R. & Reynolds J.S. (2004) Food supplementation and possible mechanisms underlying early breeding in the Florida scrub-Jay (Aphelocoma coerulescens). Hormones and Behavior, 46, 565-573
- Scheuerlein A. & Gwinner E. (2006) Reduced nestling growth of East African Stonechats Saxicola torquata axillaris in the presence of a predator. Ibis, 148, 468-476
- De Neve L., Soler J.J., Ruiz-Rodriguez M., Martin-Galvez D., Perez-Contreras T.A.S. & Soler M. (2007) Habitat-specific effects of a food supplementation experiment on immunocompetence in Eurasian Magpie Pica pica nestlings. Ibis, 149, 763-773
- Heath S.R., Kershner E.L., Cooper D.M., Lynn S., Turner J.M., Warnock N., Farabaugh S., Brock K. & Gracelon D.K. (2008) Rodent control and food supplementation increase productivity of endangered San Clemente Loggerhead Shrikes (Lanius ludovicianus mearnsi). Biological Conservation, 141, 2506-2515
- Bourgault P., Perret P. & Lambrechts M.M. (2009) Food supplementation in distinct Corsican oak habitats and the timing of egg laying by blue tits. Journal of Field Ornithology, 80, 127-134
- Eeva T., Sillanpaa S. & Salminen J.P. (2009) The effects of diet quality and quantity on plumage colour and growth of great tit Parus major nestlings: a food manipulation experiment along a pollution gradient. Journal of Avian Biology, 40, 491-499
- Barnett C.A. & Briskie J.V. (2010) Silvereyes Zosterops lateralis increase incubation attentiveness in response to increased food availability. Ibis, 152, 169-172
- Harrison T.J.E., Smith J.A., Martin G.R. & Chamberlain D.E. (2010) Does food supplementation really enhance productivity of breeding birds? Oecologia, 164, 311-320


Bay Invaders Destroy Native Species’ Food
By Jane Kay, San Francisco Examiner
March 20, 1996
212 non-natives found in estuary, more than twice that anywhere else
Clams, crabs, shrimp, worms and other tiny marine animals hitchhiking on oceangoing ships have turned San Francisco Bay and the Delta into North America’s most invaded estuary, a new study says.
The study will be released by the U.S. Fish and Wildlife Service in Washington, D.C., Friday, the same day that Sen. John Glenn, D-Ohio, intends to introduce legislation that would prohibit ships from discharging organism-laced ballast water in estuaries.
The ballast water is the main way that these species, called biological invaders, arrive — and the number of species popping up has increased dramatically in the last 10 to 15 years, according to authors James Carlton, director of maritime studies at Williams College at Mystic Seaport, Conn., and Andrew Cohen, a marine biologist at UC-Berkeley.
Researchers found 212 non-native plant and animal species established in the Bay and Delta, more than twice the number in the Great Lakes or any other aquatic ecosystem.
In the last decade, arrivals of such intruders as the New Zealand sea slug, Chinese mitten crab, Atlantic Ocean green crab and Asian clam are escalating at a rate of one new species every three months.
“The number of invasions coming in are astonishing,” Cohen said. “We’ve had a whole portion of the Bay fauna subjected to invasions in the last decade or two as a result of ballast water.”
The legislation that Glenn will propose would require vessels to discharge into the open ocean the tons of water they carry to provide balance and buoyancy. In the ocean, the escaped organisms would be less likely to disrupt the native flora and fauna.
Current regulations ban the dumping of ballast water only in the Great Lakes and the Hudson River. In those two water bodies, the European zebra mussel, for one, has multiplied, clogging pipes at municipal water and power plants and fouling ships. So far, it has caused $5 billion in damage in the United States.
Dating from the Gold Rush, when the Atlantic barnacle stowed away as the Bay’s first observed biological interloper, the creatures came on ship hulls or in fresh seafood sold at markets. Some, like the striped bass, were planted to start a commercial fishery.
Unchecked by natural predators and conditions, they reproduce by the millions, chasing out native species. While the zebra mussel and the kudzu vine in the Deep South are dramatic examples, the effects in the Bay are more subtle, the authors say – though no less profound.
The newcomers can pose a threat to biodiversity by altering ecosystems. They munch native marine life, mow down food supplies and occupy territory, Carlton said.
The Asian clam, first seen in 1986, is now the most common clam in the Bay. Too small to replace native clams as a delicacy, the little mollusks are voraciously grazing on the Bay’s food supply.
In Suisun Bay for much of the year, the Asian clam consumes most of the phytoplankton and some zooplankton, tiny plants and animals at the base of the food web, Carlton said.
The New Zealand sea slug, discovered in the Bay in 1992, already has spread to the coasts of Bodega Bay, Monterey and San Diego, including Mission Bay, said Terry Gosliner, senior curator of invertebrates at the California Academy of Sciences in San Francisco.
“Playing Russian roulette”
“There are literally millions,” he said. “Most of the species stay in bays. This one made it to the outer coast, and it’s a cause for real concern.”
At first, the sea slug was feeding on the Asian clam. “By the time it got to Bodega Harbor, it started feeding on native clam, the primary food source of our native wading birds,” Gosliner said.
Gosliner supports legislation to keep ballast water out of the nation’s ports.
In San Francisco Bay, the remaining native species, already depleted by overfishing, pollution and other environmental factors, are much more susceptible to competition from more aggressive species uncurbed in the Bay, he said.
“We’ve been playing Russian roulette with ballast water for years,” he said. “Maybe 90 percent of the species are relatively harmless. But we know from experience that some of these species have serious detrimental effects.”
©1998 San Francisco Examiner, Page A 4


"The clear takeaway is that wildfires, smoke, and the conditions that increase fire risk are national health concerns that spread well beyond the borders of local fire perimeters, conditions that are only projected to worsen with climate change," a new NRDC report says - Oct 25, 2013
Wildfire smoke endangers the health of millions of Americans, including some who live far away from those fires because of smoke that can drift hundreds of miles, according to a new report issued by the Natural Resources Defense Council. People living in Texas, Illinois, and Florida are most affected, it states.
Other states with a major impact in 2011 -- such as asthma attacks, pneumonia, and chronic lung diseases -- included Missouri, Georgia, Louisiana, Michigan, Alabama, Oklahoma, Iowa, Arkansas, Mississippi, Kansas, Tennessee, Colorado, New Mexico, Nebraska, Indiana, South Carolina, and Minnesota, according the the "Where There's Fire, There's Smoke" report, which urges that action be taken to curb the threat of climate change.
"There's trouble in the wind: What blazes in Texas rarely stays in Texas. Wildfire smoke can pose serious health risks to people hundreds of miles away from the sources of fires," said Kim Knowlton, a senior scientist in NRDC's Health and Environment Program, who directed the analysis featured in the report. "Wildfire smoke already clouds the skies of millions of Americans and because climate change will fuel more wildfires, that danger will rise. Communities need safeguards against this smoky peril, and our country needs standards to curb the unlimited carbon pollution from power plants that's driving climate change."
Oct 25, 2013


Sensitivity - the difference between a small and a large diaphragm DPA microphone.
A condenser microphone's capability of handling large SPLs is limited by two things:1. The microphone capsule, where the distance between the diaphragm and the back plate, together with the rigidity of the diaphragm, sets limits for how much a diaphragm can move before the distortion is too high. 2. The power supply for the microphone preamplifier sets limits for the amount of signal that can be handled before clipping occurs. The smaller and stiffer diaphragm will therefore be able to handle relatively higher SPLs than the microphone with a large diaphragm. SPL - the difference between a small and a large diaphragm DPA microphone.
As the omnidirectional microphone is sensing small differences in the air pressure (sound waves), both large and small diaphragms will, in principle, be equally capable of picking up low frequencies. The lower limiting frequency (LLF) of the pressure microphone is set by a small vent, to prevent the diaphragm from moving due to changes in the ambient barometric pressure. According to the dimensions of the vent (i.e. diameter and length) it will act as an acoustic low cut filter. The upper limiting frequency (ULF) is set by several factors, all related to the dimensions of the diaphragm. 1. A large diaphragm tends to break up and will no longer act as a true piston. This phenomenon is also known from loudspeaker technology and is the reason why loudspeakers are manufactured with different sizes of diaphragms to handle different frequency areas. 2. The weight of the diaphragm will attenuate the displacement of the diaphragm for higher frequencies. 3. The diffractions around the edges of the microphone capsule will limit the microphone's capability of handling very high frequencies. The conclusion is that a large diaphragm microphone will have a more limited frequency range than a small diaphragm. This is illustrated in the graphs below that show the difference in frequency range. Frequency Response - the difference between a small and a large diaphragm DPA microphone.
When a microphone is placed in a sound field, its mere presence will influence the sound itself. This is due to the acoustic phenomena that can occur around the microphone due to the size of the microphone capsule, how it is positioned, the shape and the size of the microphone body containing the preamplifier, and the connector and design of the protecting grid. All flat fronted omnidirectional microphones become increasingly directional for higher frequencies. High frequency sound waves coming directly from the front of the microphone will be reflected at the surface of the diaphragm, creating a sound pressure build-up between incoming and outgoing sound. This phenomenon occurs when the wavelength of the sound becomes comparable with, or is smaller than the diameter of the diaphragm. The relation between diaphragm size and directionality for higher frequencies are illustrated below. Directional Characteristics - the difference between a small and a large diaphragm DPA microphone.
A small diaphragm microphone can usually offer a higher dynamic range than a large diaphragm microphone. To explain this it is useful to understand how the dynamic range is calculated.
The most sensible method of calculation is establishing the difference in dB between the noise floor and SPL where the microphone produces a certain amount of total harmonic distortion (THD). We have seen earlier how the noise floor of the microphone rises if the diaphragm is small, but the SPL handling increases even more compared with the large diaphragm. This is illustrated in the table below, which shows how the dynamic range is calculated for DPA's omnidirectional studio microphones. Dynamic Range - the difference between a small and a large diaphragm DPA microphone.
Small diaphragm microphones can therefore have an equal or better dynamic range. The dynamic range is just shifted to cover different SPLs. In addition, the dynamic range of DPA's Series 4000 Professional Microphones is calculated from measurement results, where both the microphone capsule and the preamp are included in the measurement. This may sound obvious but DPA is one of the few, if not the only, manufacturer of studio microphones calculating dynamic range from all acoustic measurements.
Both diaphragm sizes have their respective advantages and disadvantages. This is illustrated in the table below, which compares the specifications of DPA's small, medium and large diaphragm microphones. Comparison - the difference between a small and a large diaphragm DPA microphone
In Microphone University we have loads of content that could be relevant to you. Learn more by reading the articles below.


S: Harriet Tubman
FC: Harriet Tubman By :Cynthia Pelayo
1: Harriet Tubman By:Cynthia Pelayo
2: It all started out in Dorchester County, Maryland in 1821 where Araminta Ross, also known as Harriet Tubman, was born to her parents, Benjamin Ross and Harriet Green. | As a child Harriet was tooken care of by slave women who were trained to take care of slave children.So if you want to lean more you can keep reading. | In 1821 out in Dorchester Country, Maryland Aramita Ross (Harriet Tubman) had a mother Harriet Green,and a father Benjamin
3: When Harriet was 20 she got married. Once she was married she fleed to free land.And when she ran away she stopped at the underground rail road.And knocked on the door,a woman opened the door and told Harriet to sweap the porch.Then the woman let Harriet in.Then in the morring she went to free land.
4: When she made it to free land she went back to set other slaves free. When she went back she lead three hundred slaves free.And didn'tleave any behind
5: Death 1820- 1913 Today I think Harriet would be remembered for bravery and being a fearless conductor on the underground railroad.And she will also be remembered for all the slaves she set free.And leading them to free land to start their new lifes as free people.
6: Accomplishment Harriet accomplished freeing three hundred slaves and leading them to free land.
7: Works Cited Koester-Grack, Rachel A. The story of Harriet Tubman. New York: Kate Ciffod Larson, 2003. McGill, Sara Ann. “Harriet Tubman.” EBSCohost 2005: 1of3. 12 Mar. 2009


For students entering grades 6 & 7
This program is designed for students who are ready to extend their knowledge, skills & abilities to use programming in real world applications such as building apps and games at a more advanced level.
Goals & Benefits of this Program:
- Develop computational thinking skills
- Participate in local coding challenges and competitions
- Exposure to guest speakers and local community professionals and companies
Day/Time: Mondays, 3:30-5:00 pm
Start Date: Monday, September 13, 2021
End Date: Monday, June 6, 2022
Location: West Vancouver Secondary School
Students interested in this course must first fill out the Student Information Form to receive a full application package.
Mr. Jeffrey Huang
Mr. Jeff Huang currently teaches at École Sentinel Secondary in the areas of Math and Science. He is also part of the school district’s Digital Innovation Team. Mr. Huang has a good understanding of programming and yet also understands how to work with students of all grade levels and within a specialized program. Mr. Huang is passionate in teaching young students valuable skills that are highly coveted in the local industries today.


About the Act
The Occupational Health and Safety Act (OHSA) contains definitions in addition to the content under the following headings:
- Part I Application
- Part II Administration
- Part II.1 Prevention Council, Chief Prevention Officer and Designated Entities
- Part III Duties of Employers and Other Persons
- Part III.0.1 Violence and Harassment
- Part III.1 Codes of Practice
- Part IV Toxic Substances
- Part V Right to Refuse or to Stop Work Where Health or Safety in Danger
- Part VI Reprisals by Employer Prohibited
- Part VII Notices
- Part VIII Enforcement
- Part IX Offences and Penalties
- Part X Regulations
These are some of the terms more commonly used in the Act.
Any place in, on or near to where a worker works. A workplace could be a building, a mine, a construction site, an open field, a road, a forest, a vehicle or even a beach. In determining whether a place is a workplace, the Ministry of Labour, Immigration, Training and Skills Development (MLITSD ) will consider questions such as: Is the worker being directed to work there?
Worker means any of the following, but does not include an inmate of a correctional institution or like institution or facility who participates inside the institution or facility in a work project or rehabilitation program:
- A person who performs work or supplies services for monetary compensation.
- A secondary school student who performs work or supplies services for no monetary compensation under a work experience program authorized by the school board that operates the school in which the student is enrolled.
- A person who performs work or supplies services for no monetary compensation under a program approved by a college of applied arts and technology, university or other post-secondary institution.
- Such other persons as may be prescribed who perform work or supply services to an employer for no monetary compensation.
A person who employs or contracts for the services of one or more workers. The term includes a contractor or subcontractor who performs work or supplies services and a contractor or subcontractor who undertakes with an owner, constructor, contractor, sub-contractor to perform work or supply services.
A person who undertakes a project for an owner and includes an owner who undertakes all or part of a project by himself or by more than one employer.
While the identification of a constructor is a fact-specific determination, the constructor is generally the person (such as the general contractor) who has overall control of a project. See also the publication entitled: Constructor Guideline: Health and Safety.
Prescribed means specified in regulations made under the Act.
A person, appointed by an employer, who has charge of a workplace or authority over a worker.
An owner includes a tenant, lessee, trustee, receiver, mortgagee in possession or occupier of the lands or premises. It also includes any person who acts as an agent for the owner.
A person who holds a logging licence under the Crown Forest Sustainability Act, 1994.
- Regularly Employed
This term is not defined in the OHSA. However, by policy, MLITSD has interpreted the term to mean employed for a period that exceeds three months.
- Workplace Harassment
Workplace harassment is defined in the OHSA as engaging in a course of vexatious comment or conduct against a worker in a workplace that is known or ought reasonably to be known to be unwelcome.
- Workplace Violence
Workplace violence is defined in the OHSA as the exercise or attempted exercise of physical force by a person against a worker, in a workplace, that causes or could cause physical injury to the worker, or a statement or behaviour that it is reasonable for a worker to interpret as a threat to exercise physical force against the worker, in a workplace, that could cause physical injury to the worker.


Notch filter is known as band-cut filter or band-reject filter. The fuction of this filter is to remove some frequency portion of a signal. The schematic diagram of this filter circuit, a second order notch filter is depicted in the figure below.
The formula is actually complicated, but by taking the R3=R4 and C1=C2, the filter’s frequency response formula become very simple, as shown in the figure above. By selecting C1, C2 = 47 nF, R1, R2 = 10 k, R3, R4 = 68 k, you’ll get a frequency respon of 50Hz notch, similar to hum filter in our previous circuit ( hum filter using op-amps and hum filter using transistor).