A group of European catfish in Southwestern France has learned to catch pigeons, as they get close to the River Tarn. European catfish (Silurus glanis) can grow up to 1 to 1.5 meters long and are the largest freshwater fish in Europe.
The scientists published their findings in the journal PLOS ONE. S. glanis accomplishes this feat by lunging out of the water, grabbing a pigeon, and then wriggling back into the water to swallow their prey. This process leaves the fish stranded on land for a few seconds.
Bottlenose dolphins have been observed using a similar technique in South Carolina, as have Argentinian killer whales, which actually swim onto beaches to snag resting sea lions. Researchers were alerted to this behavior by local fishermen. Over the summer of 2011, they filmed 54 attacks, of which 28% were successful.
The erect barbels on S. glanis‘ upper jaws, combined with the fact that only moving pigeons were attacked, indicates that the fish are sensing the vibrations of the birds as they approached the water.
For now, scientists don’t know what prompted this predatory behavior on the part of S. glanis and whether they gain any benefit from it. S. glanis was introduced to Tarn in 1983 and the breed is flourishing. It’s possible that the catfish have eaten too many of the local fish and have been forced to seek additional prey.
Reference: ““Freshwater Killer Whales”: Beaching Behavior of an Alien Fish to Hunt Land Birds” by Julien Cucherousset, Stéphanie Boulêtreau, Frédéric Azémar, Arthur Compin, Mathieu Guillaume and Frédéric Santoul, 5 December 2012, PLOS ONE.