Those crocodiles are so smart and tricky. New evidence has been found that they hide on the surface of water under twigs during waterbird nestbuilding season, when they know that birds are looking for all the twigs they can find to build their nests. This means when a bird grabs one of those twigs . . . SNAP! An easy meal for the crocodile. American alligators display this behavior, too.
http://blogs.scientificamerican.com/tetrapod-zoology/2013/11/30/tool-use-in-crocs-and-gators/
http://blogs.scientificamerican.com/tetrapod-zoology/2013/11/30/tool-use-in-crocs-and-gators/