Birds get a lot of attention for their use of tools. Clever animals, birds. But non-avian reptiles are capable of equally complex behaviors. Recent observations of crocodiles and alligators have revealed that both use twigs as hunting lures. A poetic twist: The sticks are used to lure birds. (WHO'S THE CLEVER ONE, NOW?)
Above: An American alligator successfully catches a Snowy egret (Egretta thula) following stick-luring behavior. Photo by Don Specht via Dinets et al. Used by permission.
As described by Dinets et al. (2013), Mugger crocodiles Crocodylus palustris in India and American alligators Alligator mississippiensis in the USA have both been observed to lie, partially submerged, beneath egret and heron colonies with sticks balanced across their snouts. Birds approach to collect the sticks for use in nest building and… well, let's just say that it doesn't end well for the birds. If the crocodylians really are using the sticks as bait to attract their bird prey, this is tool use, since the sticks are objects that are being employed for a specific function.
The occurrence of sticks on the crocodylians is not random: stick-displaying behaviour was most frequently observed both in those crocodylians living at rookeries and was exclusively observed during the egret and heron nesting season, being most frequent in late March and April (when the egrets and herons are working hard to find sticks) (Dinets et al. 2013).
The observations of Dinets and his colleagues are recounted in the latest issue of Ethology Ecology & Evolution, where they write:
Using objects as hunting lures is very rare in nature, having been observed in just a handful of species. We report the use of twigs and sticks as bird lures by two crocodilian species. At least one of them uses this method predominantly during the nest-building season of its prey. This is the first known case of a predator not just using objects as lures, but also taking into account the seasonality of prey behavior.
Much more over at Tetrapod Zoology (where Dinets has made an appearance in the article's comments). See also: Dinets' recently published Dragon Songs, which discusses the discovery of tool-use and other recently observed crocodilian behaviors (some of which remain unpublished).