After I had been playing with this coot, and been quite close to him after a couple of years, I tried to do coot research on the internet. I was quite confused and frustrated when many things I read just didn't make sense. Here in the small marina basin there are usually only about five or six coots in the winter, and it is easy to see them as individuals and understand their behavior.
Coot behavior and general lifestyle is surprisingly varied and complex. I can only guess that most of the information available is based on distant casual observations and inaccurate assumptions. The most accurate and professional study of coot behavior widely available is from the Wilson Bulletin THE DISPLAYS AND CALLS OF THE AMERICAN COOT June, 1952 (volume 64 no. 2) pp 83-97.
THE DISPLAYS AND CALLS OF THE AMERICAN COOT
This and five other ornithological journals are available from the University of New Mexico at: http://elibrary.unm.edu/sora/. I find this source of information to be quite professional and accurate, and follows my own experience and observations. At least 15 articles are available relating to coots, but you can search for information on your favorite bird at this site. For the links to other sites below, Caveat Emptor !The following comments and examples are my own opinion, taken from my observations, or things I have read that seem reasonable. It's unfortunate that the coots don't nest or mate here and I can't observe that behavior in detail.
It seems that most coot misinformation comes from the difficulty of determining the sex of birds being observed. Each coot has its own "voice" or sound. The male has a relatively higher pitched "squawk" similar to the sound of air brakes on some large trucks. The female is recognized by a low pitched croak or nasal "punt" sound. Each bird can vary the sound somewhat by making softer "peeps" or short "yips", but usually with the same voice. At times of stress, the male can produce a somewhat higher pitched yip followed by the normal squawk. The female can produce a low pitched "clucking" sound, hence the common name "mud hen". Researchers have noted how difficult it is to interpret bird sounds in writing, but this still doesn't seem to discourage ambiguous and sometimes comical attempts like this.
Voice Differences Between Sexes in the American Coot
Except for migration and common defense, coots are always defending their own small patch of real estate. Two determined coots may fight to the death with one holding the other under water until it drowns. The majority of calls and displays of the coot relate to defending territory.
Coots fight in the water by slapping each other with their feet, and trying to force the other coot under the water. Most often the defeated coot will swim a long way under water to escape.
Coots rarely engage in combat out of the water, but when dominant males are fed by the sidewalk they may eat first, and fight later.
Regardless of their territorial nature, coots always flock together for protection. Everyone knows how a school of fish works to confuse predators, but coots will join any other species that happens to be handy. A study in Germany showed that coots that joined geese while foraging were able to spend more time eating and less time watching for danger, and thus improve their foraging efficiency. The few coots here often hang around the periphery of mallard duck groups. A coot would be helpless to take food from the larger and more powerful goose or duck, but can take advantage of the other bird's alertness to warn of danger.
When a large sea lion appeared eating a fish, Beaky the Coot was horrified and immediately joined a pair of grebes nearby, until they were safely across the open water. He went to the far side of the marina basin and stayed away for the rest of the day.
I have noticed that this coot comes to me and stays nearby even when not interested in eating. I have guessed that this behavior is similar and is only for security.
Two coots often turn their backs to each other and fan their tail feathers as a peacock would. Many observers immediately see this as a mating behavior, but are taking it completely out of context. This display always follows a territorial dispute, at the border of two territories, and mostly involves two males. Any number of coots up to five or six can participate. The paired display is similar to the danger display shown above except the head is usually lowered in the hostile attitude. The danger warning display is considered friendly with the bird's head raised.
The following shows a charging coot with a ruff on his neck attacking another male coot that is giving the paired display. The charging coot broke off his attack and ran away upon seeing the other coot's display.
A mated pair of coots follow a display called bowing, billing, and nibbling. Usually, I only notice the bowing, as an invitation, and the nibbling.
The birds really like to have their heads scratched and preened by their mates.
After a brief separation, mates may mutually dabble their beaks in the water. This is a sign of peaceful recognition, and may be a form of displacement feeding.
Unlike most birds, coots lay a number of eggs (usually averaging nine per clutch) but start incubation upon laying the second egg. This means they hatch out at the rate of approximately one per day for about eight or ten days. This obviously causes a logistics problem in rearing the young. A pair of coots usually builds eight or nine nest like structures for different purposes. Two nests are used for babies. One is used for incubation of the eggs while a second one may be used for rearing the chicks. Other "nests" can be used for display, mating, or sleeping (roosting).
Since coots start continuous incubation early in the laying period, this would reduce the possibility of death from chilling of the eggs. However, after the chicks are hatched, the parents will tend to shift from incubation to brooding when they see a large number of mouths to feed. At some point they may dump unhatched eggs in the water and concentrate on feeding the new chicks. Usually fewer than eight chicks hatch.
You may hear stories about coots killing their young for whatever reason. Because of their asynchronous incubation, an age difference of as much as ten days is common in a large clutch. Babies with age differences of ten days may look quite different, and mothers are seen alternately feeding and attacking their own chicks in confusion. They will not care for another coot's chick. The parents may also "hide" some of their younger babies while foraging with their other chicks. This also causes great disagreement among human researchers who place the coots incubation period as anywhere from 14 to 30 days. The actual incubation period is 23 to 25 days.
The size and shape of the frontal shield at the top of the upper mandible is unique for each bird. Researchers made this assumption since a bird may attack its mate from behind by mistake, immediately stopping when face-to-face. I have found that the shape of any bird's frontal shield may vary slightly over a period of several weeks, returning back to normal. The cause of this is unknown. Researchers reported being able to recognize individual birds by their "face". I found this ability to extend to humans also, since coots can recognize people as individuals and will patiently follow people who will feed them and avoid others. Beaky was once confused and frightened by my wearing a bicycle helmet, but he soon overcame the problem of hats. I have seen him staring at my shirt recently, apparently trying to resolve the difference in my winter clothes. Coots will also study my face carefully, especially if I do something unexpected.
The size of the frontal shield is also important in indicating the social status of a bird. A dominant male defending territory will have a more swollen shield. This is the effect of increased testosterone in the male. Experiments with drug implants in nonaggressive males shows that this drug causes a swollen frontal shield. This makes other birds afraid of the newly swollen male, but it does not make the male aggressive and other birds soon ignore this.
Many observers see the coot's habit of bobbing its head back and forth as a cute idiosyncratic behavioral tick, or relate it to leg movement. If you watch a coot's leg movements, you can see that it is not related. As an example, coots don't move their heads at all when charging or patrolling with an aggressive posture. Researchers have found that the head movement relates to the type of food the bird is hunting while foraging. The theory is that the head movement is used to resolve a parallax problem in seeing things in water.
My theory is that, since the coot has similar head movements when out of the water, this is a way of getting depth perception from a single eye. A coot often studies me with one eye while darting its head side to side. The bird's eyes are so far separated that adapting to this technique could be a way of getting binocular vision with one eye.
Missy shows her right foot in the picture above. Each segment of the bird's toes are called lobes. The lobes have flaps that open and spread apart when the coot pushes on the water. The flaps fold together when the foot is drawn forward.
Coot feet may become infected resulting in swelling of the black ball where the toes meet.
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These two pictures at right were taken at Chollas Lake in July of 2008. |
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A female coot with two chicks is shown above, and a juvenile coot is shown at right. |
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Coots are like people. Lifestyle and gender roles in foraging, nesting, incubation, rearing chicks, and defending territory can vary. What I have read about coots makes me feel that the behavior of this one coot, in his relationship to people, is perhaps uncommon, but not surprising. New migrant coots may come to me, run away from me, or ignore me. They all have different personalities. You shouldn't think you can make any sense out of one or two observations. Sometimes it seems almost automatic to make hasty, inaccurate conclusions, and present them as if they were fact.
American Coots make an excellent subject for the study of animal behavior. These birds have a large variety of calls and displays, and they are friendly and social with people. Their emotional nature makes it easy to understand what they are thinking, but you always run into trouble when you try to explain animal behavior in human terms. Don't be surprised if you find reputable research to be contrary to your own observations. The following quotation from The Outermost House, a classic of American nature writing by Henry Beston, expresses my frustration at trying to understand these friendly little birds. The more I learn about them, the more mysterious they become:
" We need another and a wiser and perhaps a more mystical concept of animals. Remote from universal nature, and living by complicated artifice, man in civilization surveys the creature through the glass of his knowledge and sees thereby a feather magnified and the whole image in distortion. We patronize them for their incompleteness, for their tragic fate of having taken form so far below ourselves. And therein we err, and greatly err. For the animal shall not be measured by man. In a world older and more complete than ours they move finished and complete, gifted with extensions of the sense we have lost or never attained, living by voices we shall never hear. They are not brethren, they are not underlings; they are other nations, caught with ourselves in the net of life and time, fellow prisoners of the splendour and travail of the earth."
This is saying that these animals are perfect for the natural world they live in. Unfortunately, that natural world is very nearly gone.
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