Cats hunt birds, and sea-birds hunt fish. And in some odd ecological pockets, catfish hunt pigeons.

In a study published today by researchers at the University of Toulouse, France, scientists have investigated this unusual predator-prey relationship between European catfish and pigeons in the Southwest region of France.

European catfish have been reported to capture the pigeons on land and drag them back into the water. This surprising behavior has not been known to occur in the native range of the species; however this article discovers that in France, where the fish are an invasive species, they have adapted their natural behavior in order to feed on novel prey in their new environment.

The researchers completed this study along the Tarn River in Southwestern France. European catfish originate from Europe, east of the Rhine River, but were introduced to the Tarn River in 1983.

From a bridge above a gravel island on the river, the researchers watched the fish from June through October 2011. Over that time they saw 54 pigeon hunting incidents, and in 28% of these cases, the catfish successfully captured their prey on land and dragged them back into the water to eat them. These attacks were nearly always triggered by active pigeons, as catfish never attacked motionless pigeons. This evidence suggests that the catfish used water vibrations to hunt their prey rather than visual cues.

The cause of this unusual predation behavior is still unknown. However, these new findings may bring us closer to understanding the implications of such novel behavior in a new ecosystem.

To view the fascinating catfish behavior described in this article, please see the video below:

http://www.youtube.com/watch?v=g1y7ASI3ZkQ

Citation: Cucherousset J, Boulêtreau S, Azémar F, Compin A, Guillaume M, et al. (2012) “Freshwater Killer Whales”: Beaching Behavior of an Alien Fish to Hunt Land Birds. PLoS ONE 7(12): e50840. doi:10.1371/journal.pone.0050840