Upon first glance the american coot, Fulica americana, is not particularly impressive. With its solid black body, red eyes and white bill, you might think that it is just a duck. But beware! This is a very common misconception that I myself had. The american coot might look like a duck and swim like a duck, but its behavior and call indicate that it is anything but a duck. The american coot is quite boisterous, and its call is unique. In fact, in a large group it can be very loud and dissonant. Often when I think of a birdcall I imagine the sweet sounds of a cardinal or wren. With that said, after only a few minutes I realized that is not the type of sound that comes from the coot. The primary call sounds very similar to a bunch of dogs each having its way with an old chew toy. It is both high pitched and short in duration. However, it’s not surprising that these birds have distinct calls since they rely heavily on auditory communication. As chicks mature, so do their vocalizations, leading to complex behaviors such as flocking and migration.
I recently observed a flock of american coots at Brazos Bend State Park near Needville, Texas. They were in a very large group consisting of approximately fifty individuals. Interestingly, they were also paired off in that larger group. I was unable to tell whether these pairs were of the same or different sex since male and female coots look very similar. The pairs would frequently chase each other and also dive underwater in what appeared to be a playful, teasing manner. I think that their behavior was all in good fun since there was no apparent irritability from the participants. Some could be seen splashing themselves with water, and others diving below the surface to eat. Additionally, the group as a whole seemed open to other water birds sharing their space. Black-bellied whistling ducks and spoonbills were found in the same general area with what appeared to be little reaction from the coots.
Curious to know more about the species I turned to the literature, primarily papers found on Google Scholar. A significant amount of work has been done concerning the behavior and lifestyle of the american coot. Large body size differences between young and old coots have been observed. Older coots tend to be larger than younger ones and in their paper, Ray Alisauskas and Davison Ankney argue that older females have higher protein reserves, which in turn results in the larger body size. Alisaukas and Ankney’s study took place in Manitoba, a province in central Canada, in 1981 and furthermore, they suggest that these increased protein reserves are likely due to large, well defined territories that allow the older females better foraging opportunities as compared to a younger less established coots.
This difference in size also leads to different clutch behavior. It is not uncommon for american coots to lay eggs in the nests of other females. Conspecific brood parasitism, or laying eggs in the nests of other birds of the same species, has been observed in many species including the coot. Seen as a reproductive strategy, some females do this in addition to laying full size clutches of their own. Bruce Lyon studied this behavior over four years in central British Canada in the early 1990’s. He found that by laying eggs in other nests, american coots are able to avoid the hard work involved in prenatal care while also increasing their total offspring. Who said raising baby coots was easy? By placing eggs in other nests, coots are able to increase their odds of having lots of offspring while also keeping more resources such as food for themselves. Instead of sharing food and shelter with many young, coots that parasitize other nests at high rates are able to keep those additional reserves for themselves making them larger and healthier. This begs one to question why another coot would care for eggs that are not its own. The answer lies in the fact that they can’t tell! American coot eggs vary widely in size, shape and color (see picture below). Thus, another coot is unlikely to remove eggs from its nest in fear that they are removing one of their own! Lyon also states that it is possible that parasitism could be a temporary strategy. Smaller, younger coots could primarily employ this mechanism due to lack of territory or a nest. Also poor living conditions such as lack of food can cause increased parasitism.
As if being placed in the wrong nest wasn’t enough, baby american coots have another challenge, competition among their peers. The same environmental constraints that lead to parasitism also cause coots to selectively feed their young. If other chicks want to survive, they must rely on their own skills to obtain food. In 1984, Barbara Desrochers and Davison Ankney found that adult american coots with larger brood sizes feed their young nearly five times more often than those with smaller brood sizes. To be more exact, adult coots with large brood sizes fed their young once every 2 minutes while adult coots with smaller brood sizes fed their young once every 10 minutes. Parents also wean their young in order to foster independence. Surprisingly, brood size had no effect on the behavior of offspring leaving their parents.
After reading all the literature one thing stands out – being an american coot is hard work! Although they don’t seem very complex on the surface, its obvious that coots are the perfect example of birds that are struggling to make it to the top. The benefits of being old and fat make for a good life. This definitely can’t be said for all species, including our own. So remember, the next time you see an american coot don’t think that it’s a duck, recall that it’s a water bird that’s just trying to make it in a hard, hard world.
Here are some of the references I used in this entry.
This paper focuses on how the size of american coots is influenced by diet, age and territory.
This paper discusses the american coot’s vocal developments and the importance of its calls in behavior. It also describes the four different calls that coots make in order to communicate.
This paper discusses how the varying size of broods can impact parental american coot’s feeding habits.
This paper considers the parasitic behavior of american coots and how and why this reproductive strategy is beneficial for the species.
This paper goes into more detail about the mechanisms and reasons american coots perform brood parasitism.
Two american coots coots fighting. Photo taken by Kevin Cole (public domain)
Female american coot with two chicks. Photo taken by Mike Baird (public domain)
The above graph is taken from the 2003 Lyon paper in the Journal of Animal Ecology. The graph illustrates how american coots with a smaller body mass are more likely to participate in brood parasitism versus their larger counterparts. Again we see the theme of the larger the coot the larger the brood size and the smaller the need to parasitize other nests.
The above picture is taken from the 1993 Lyon paper in Animal Behavior is of several american coot eggs from 20 different birds. Each row represents eggs from the same female. Coot eggs widely differ in size, shape and color as indicated in the photo.
This image is an example of a parasitized coot nest. The two darker eggs in the nest belong to a different coot (Photo by Bruce Lyon).
The above graph taken from the Desrochers and Ankney 1986 paper in the Candian Journal of Zoologoy illustrates how as american coots age, they become more successful at feeding themselves and obtaining food from sources other than their parents.
This image is of the distribution map of the american coot. They are primarily in the southwest portion of North America but can be found in the North and Southeast during the summer and winter respectively (Photo from allaboutbirds.org).