Snake! Crow! Marten! Great Tits call out their nest predators

Nests of songbirds are predated by.. well, just about everything. The common nest predators are snakes, larger birds, and many mammals, particularly carnivores. A recent study by T. Suzuki showed that Great Tits (relative of North American chickadees) are able to vocalize the identities of three nest predators. Jar calls are used to identify snakes and they different rates of chicka calls to discriminate between martens and crows. 

Martens are in the weasel family. I don't have a picture of a marten, but below is a road kill mink that I found in Dallas, Pennsylvania.

 

Link to article: http://dx.doi.org/10.1016/j.anbehav.2013.10.009