Crocodiles and alligators apparently use small sticks to attract water birds and prey on them, according to a new University of Tennessee study.

Zoologists said that mugger crocodiles in India, and alligators in Florida and Louisiana, seem to be aware of the seasons when birds come to collect twigs to build nests. The predators balance small twigs on their snouts to lure birds, which appear to be floating on the water.

The animals lie partially submerged near the colonies of herons and egrets with sticks balanced across their noses. They wait until a bird comes to collect the stick before pouncing.

Vladimir Dinets, a Zoologist and author of the study told Wired.co.uk that alligators "know exactly when and where egrets build nests" and "float around with sticks in the right place at the right time".

After observing the reptiles' behaviour across the sites, the zoologists found that the stick baiting behaviour was only observed during the bird's breeding and nest-building season from March to April. During the study period, at one instance, they observed a crocodile grabbing hold of an egret when it came to collect a stick.

"Using objects as hunting lures is very rare in nature, having been observed in just a handful of species," according to the study. "At least one of them uses this method predominantly during the nest-building season of its prey," Daily Mail UKreports.

"This is the first known case of a predator not just using objects as lures, but also taking into account the seasonality of prey behaviour. It provides a surprising insight into previously unrecognised complexity of archosaurian behaviour."

Zoologists said that normally bird species prefer to build nests in trees growing in ponds because the reptiles protect them from tree-climbing nest predators such as snakes, monkeys and racoons. However, birds pay the price for building nests close to reptiles. Crocodiles and alligators gobble any chicks that fall into the water and birds that come looking for building materials.

Dinets said that although the stick baiting behaviour has been noticed only in two crocodile species, it is believed to widely exist in the group.

The study has been published in the journal of Ethology Ecology and Evolution.

Topics Bird, Prey, Tools, Food, University of Tennessee