Swamp birds sacrifice babies to alligator bodyguards

March 3, 2016, 10:48 a.m.
Birds have a gruesome partnership with alligators.
Photo: Orhan Cam/Shutterstock

In the swamps of Florida, birds have decided that when it comes to nesting success, it's best to keep alligators as close neighbors. These bodyguards will keep away nest raiders like opossums and raccoons, but for a hefty fee.

"Over time, a study released Wednesday says, egrets, herons, ibises and storks that nest on islands developed a strategy. They nestle on tree limbs near alligators, which chase and sometimes eat nest raiders. For that service, alligators demand a heavy price — some of the birds' offspring," reports The Washington Post.

Alligators seek out these tree islands of nesting birds, knowing that food will fall from above at some point. As chicks in nests grow up, sometimes one or two will be pushed from the nest. These chicks are devoured by the gators, but those remaining are typically safe from other nest raiders. The birds are willing to have danger living at their feet because it increases the chance that at least some of their chicks will survive to the fledging stage.

In fact, the study showed that the birds know full well what service the gators provide. In his story for the Post, Darryl Fears writes:

Three years ago, [the study's lead author Lucas] Nell said, a fellow researcher who was not a part of his study tested this theory. She placed fake alligators on an island long before the birds arrived during their migration, and sure enough, most of them hung out on the limbs above the fake alligators. Also telling, no raccoon or possum showed up.

The researchers found that alligators that take up a post as a bodyguard, and thus feast on both hopeful nest raiders as well as chicks that fall from the nest, are an average six pounds heavier than nearby alligators that don't have a spot under the trees. This arrangement helps breeding female alligators to have their own nesting success as well, since a thicker layer of fat comes in handy when raising young.

It's a gruesome partnership, but in nature that is red in tooth and claw, it's one that makes sense for all parties involved.

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Jaymi Heimbuch is a writer and photographer at Mother Nature Network. Follow her on Twitter, Instagram and Facebook.