The line that separates water from land is a fascinating area for biologists to study. For some aquatic animals, like the orca whale, it's a place where they can briefly step outside the boundaries of their natural ecosystem and grab a quick bite to eat. The latest example of this unique feeding behavior was witnessed by French biologists who recently observed European catfish preying upon unsuspecting pigeons with frightening proficiency — an indication that these fish are more crafty and adaptable than previously imagined.

The study was conducted by Julien Cucherousset, Frédéric Santoul, and their colleagues at University of Toulouse, France. To observe the fish, they situated themselves on a bridge overlooking the Tarn River in Southwestern France. And what they saw came as a complete shock, as catfish have never been observed to do this before.

Just as remarkable was how good the fish appeared to be at it. Of the 45 breaching behaviors observed, 28% resulted in successful bird capture. A one-in-four success rate is incredible for any predatorial attack, let alone one that transcends the water-land barrier. These 'alien' catfish, which are invasive to the southwest region of France, have clearly stumbled upon an opportunity — one made possible by flexible behaviors which have allowed them to forage on completely new prey in a foreign environment.

While observing the catfish, the researchers also noticed that the fish only attacked when the pigeons were active in the water. Motionless birds, even when in the water, were left alone. This led them to conclude that the catfish were not using visual cues to spot the birds, but by sensing water vibrations instead. Essentially, the pigeons, by their movements, were triggering the attacks.

You can read the entire study at PLOS.