What would happen to mankind if crocodiles and alligators were to develop enough intelligence that they could hunt with tools? Would we see the rise of new dominant species as in Rise of the Planet of the Apes ? Well, shudder in your boots, people, because we are already there!

In January of 2007, Vladimir Dinets, a zoologist with the University of Tennessee, noticed some mugger crocodiles in India laying in shallow water with small sticks resting on their snouts. When an egret approached the sticks, which were a perfect size for its nest, the crocodile lunged at it, narrowly missing the bird. Was this incident a premeditated hunting technique or a mere coincidence?

Dinets and two biologists from the St. Augustine Alligator Farm Zoological Park in Florida set out to determine if American alligators, another crocodilian species, purposely use sticks as hunting lures. Several species of birds prefer to breed in trees that hang over crocodilian-infested waters because of the protection that the crocodilians provide against tree-climbing nest predators such as raccoons, monkeys and snakes. In fact, most crocodile and alligator farms are sites of egret breeding grounds (called rookeries). The researchers hypothesized that if alligators are purposely using sticks to lure birds, then they should balance sticks on their noses more when they are closer to the rookeries and when the birds are building their nests at the start of their breeding season.

The researchers observed American alligators for a year at four different sites in Louisiana: 1) at a cattle egret rookery on Millers Lake, 2) 2km away from the rookery on Millers Lake, 3) at a rookery for great and snowy egrets, roseate spoonbills and white ibis on Lake Martin, and 4) 1km away from the rookery on Lake Martin. At each site, they took notes on the proportion of alligators observed with sticks on their snouts. They compared these proportions between the birds' 6-week nest-building season and the 6-weeks after nest-building is done, and between sites with and without rookeries.

The alligators were only observed to balance sticks on their snouts during the birds' breeding season. Furthermore, it was more common during the nest-building phase than later in the breeding season after the birds' nests were complete. Additionally, the alligators near the bird rookeries displayed sticks on their snouts more than alligators that were in the same lakes but far from the rookeries. Because free-floating sticks were rarely seen, the alligators were likely actively seeking sticks to perform this behavior with, demonstrating a complex behavior and intelligence that we do not generally associate with crocodilians.

We often imagine crocodiles and alligators as lazy, stupid brutes, but that is far from the truth. These animals, closely related to dinosaurs and flying reptiles, are known to show advanced parental care, complex communication, coordinated group hunting tactics and now, to use hunting lures. But don't worry, they have likely been this advanced for as long as humans have existed and they haven't taken over the planet... yet.

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Further reading and image credit:

Dinets, V., Brueggen, J.C.. and Brueggen, J.D. Crocodilians use tools for hunting, Ethology Ecology & Evolution, (2013). DOI: 10.1080/03949370.2013.858276.