In a study published in PLOS one, scientists focused on facilitation as an ecological exchange between species, whereby a species habitat is enhanced by another species. In this case, scientists studied wading birds in Florida such as egrets and herons and observed how they contributed to the American crocodile’s food supply. In exchange for the contribution from the birds, the American crocodiles engaged in a critical supportive behavior — nest protection.
In Florida and in other areas of the world, a nest full of bird eggs is a tempting meal to semiaquatic predators such as raccoons and opossums. So having an alligator nearby to protect your brood is a smart move. Wading birds will build their nests near alligators, but tall enough to avoid becoming a meal themselves, for protection. Sometimes birds lay too many eggs and adjust the brood size accordingly. Adjusting the brood size accordingly means pushing chicks out of the nest, dead or alive. When the chicks are pushed from the nest, the American crocodiles come to feast.
The study found that amount of food that wading birds provide to their protectors is sufficient enough to support large populations of American alligators. However, it did not show that the alligators associated with the wading birds were better off than those not associated.