Some birds have cleverly figured out that if they build their nests above alligator hangouts, the gators will scare away most intruders, a new study has confirmed.
The unwitting alligators benefit from the arrangement too, since they eat eggs and chicks that often fall out of the overhead bird nests, according to the study, which is published in the journal PLOS ONE.
"Our study is the first to demonstrate a mutually beneficial relationship between nesting birds and a crocodilian: nesting wading birds provide nutrition for alligators that, by their mere presence, create predator-free space for birds," co-author Lucas Nell from the University of Florida explained in a press release.
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Nell and his team note that for many bird species, attacks on nests pose the greatest threat to raising chicks. This is especially true for long-legged wading birds such as herons, egrets, ibises, storks and spoonbills. Numerous predators, like raccoons, would love to get their paws on an easy and nutritious meal of birds and eggs.
The researchers found support for prior claims that adult wading birds preferentially build their nests above alligators that, as the camera trap photo demonstrates, can easily scare off raccoons and most other animals, including humans!
Nell and his team took this finding a step further by comparing the body weight and overall condition of female alligators under the bird nests with the weight and condition of female gators located away from wading bird nesting colonies. The study took place in the Florida Everglades.
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The scientists determined that the body condition of alligators found near wading bird nesting colonies was much better than for alligators in similar habitats but without active bird colonies. This measure of health was independent of all kinds of environmental variables that the authors took into account.
The bird nests are high enough that the alligators cannot get to them. The dropped eggs and fallen chicks, however, were plentiful enough to make a dent in the "bodyguard" alligators' diet, the research indicates.
Since nesting birds and alligators, as well as crocodiles, often inhabit the same tropical and subtropical wetlands, the findings could extend far beyond the Everglades.
As Nell said, "Crocodilians and nesting birds co-occur throughout the tropics, so these may be globally important ecological associations."