Complex ecosystems often create complex interrelationships between animals. One of the more surprising ones is that between waterbirds and alligators in the Florida Everglades.
It turns out that alligators like to hang out near the nests of birds like egrets, ibises, and herons – which is no big surprise. However, the birds actually prefer to build their nests near where the alligators live, and that is definitely surprising.
A researcher at the University of Florida put out fake plastic alligators throughout the Everglades and found that wading birds do prefer to nest on tree islands adjacent to alligators. The reason is that other predators like raccoons and possums no longer are a threat to the birds. Ordinarily, if raccoons get into a nesting colony, birds abandon their nests in large numbers because they have no defense. With an alligator around, raccoons are either dissuaded from sticking around or are eaten.
So the benefit to the birds is apparent. But the arrangement is good for the alligators too. Research has revealed that alligators that have nesting colonies in their territories are healthier and weigh more than those that don’t. Clearly, some chicks are eaten by the gators, but in the big picture, it seems to work out for the best. Alligators are not just apex predators; they also are ecosystem engineers whose activities in the Everglades improve the environment.
Some have described the strange symbiosis between the birds and alligators as like having a psychopath in your yard to keep out cat burglars. But it seems to be beneficial. Alligators get occasional snacks and birds get protection from predators. Nature works in curious ways.
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Photo, posted November 15, 2009, courtesy of Phillip Capper via Flickr.
‘Alligator Security Guards’ from Earth Wise is a production of WAMC Northeast Public Radio.