Birds are using alligators in the Everglades to protect their nests from long-legged wading birds as well as from nest-raiding mammals like possums and raccoons by nesting directly above waters infested with alligators.
Alligators are the lesser of two evils?
Strangely, this does indeed seem to be the case. Birds might not be the smartest creatures on the planet but instinct and evolution make up for this as a bird’s only real purpose in life is to reproduce and clearly they think that the alligator can help.
This understanding was reached by the ecologist Lucas Nell who began a study of the bird-crocodilian relationship while working on his master’s degree in 2011 at the University of Florida.
This is not to say that birds simply lay there eggs next to an alligator risking life and limb, quite literally, or the safety of its nest and eggs. Rather, the birds are laying their eggs at least five feet up a tree over alligator-infested waters so that they and their eggs are safely out of the reach of the alligators while also using the alligators as a deterrent against the Egrets and mammals that feast on eggs.
“I kind of liken it to less of a bodyguard and more of keeping a psychopath in your yard to keep out the cat burglars,” said Nell.
“Raccoons are devastating for birds,” said Nell from his offices at the University of Georgia where he now works as a research technician. “If even a few or a handful of raccoons get into a nest or colony, the birds abandon their nests en masse.… And the raccoons just eat everything.”
Alligators don’t work as bodyguards for free
According to Nell’s study which appeared this week in the journal PLOS ONE, the birds aren’t just being clever but, rather, are paying for this protection. And in the case of paying the alligator, the currency is the chicks that ultimately hatch from the eggs the alligators were protecting.
Wading birds are social animals that form massive inter-specie nesting communities or colonies often made up hundreds to thousands of birds. The birds ultimately end of laying more eggs than the colony can support food-wise. Out of necessity, some of these chicks based on seasonal food sources are ejected from the nest and that ejection invariable ends in the stomach of their protectors.
The food chain in areas like the Everglades is a complex wonderful thing to watch and alligators reap the benefits of bird colonies. Bird waste supports plant and algae life in the waters of the Everglades which is in turn eaten by small fist and aquatic invertebrates, which in turn, provide a food source for alligators.
Nell essentially proved that alligators reap the benefits of living near a bird colony by using airboats to capture adult female alligators by night. The team captured nearly 40 in order to measure their body mass and snouts. Snouts are used to measure length as many alligators are missing the ends of their tails.
The study found unequivocally that alligators living within 200 meters of bird colonies are considerably healthier than alligators who haven’t quite figured this out enough to move.
The researchers found about a six pound difference in alligators living near within 200 meters from a colony to those a kilometer away from their avian “friends.”
Despite the fact that the Everglades are teeming with life, alligators are relegated to snacking on snakes, crayfish and small lizards.
“They don’t get an opportunity for big meals,” Nell said.
As a consequence, alligators living in the Everglades are considerably smaller than alligators of the same species living elsewhere.