A freshwater fish as a predator and with a bird as its prey!!
The European catfish was introduced into the river Tarn in in France only in 1983. This is behaviour which has developed in just about 30 years. So the genetic pre-disposition of the catfish for this kind of hunting must have already been in place. Perhaps this is further evidence that the genetic portfolio of an individual determines the range of behaviours that are possible but which particular traits actually develop or come into play are determined by the surrounding environment.
Ed Yong reports:
In Southwestern France, a group of fish have learned how to kill birds. As the River Tarn winds through the city of Albi, it contains a small gravel island where pigeons gather to clean and bathe. And patrolling the island are European catfish—1 to 1.5 metres long, and the largest freshwater fish on the continent. These particular catfish have taken to lunging out of the water, grabbing a pigeon, and then wriggling back into the water to swallow their prey. In the process, they temporarily strand themselves on land for a few seconds.
Other aquatic hunters strand themselves in a similar way, including bottlenose dolphins from South Carolina, which drive small fish onto beaches, and Argentinian killer whales, which swim onto beaches to snag resting sealions. The behaviour of the Tarn catfishes is so similar that Julien Cucherousset from Paul Sabatier University in Toulouse describes them as “freshwater killer whales”. …..
….. The European catfish is an alien, introduced into the Tarn in 1983, and currently flourishing there. Is it possible that these invaders have eaten too many local fish and are forced to seek sustenance elsewhere? Does this explain why it seems to be the smaller catfish that go after pigeons? Or is it that the smaller individuals are less likely to be permanently stranded on shore, or expend less energy in wiggling back into the water? Why, essentially, is a bird in the mouth worth being a fish out of water?
Reference: Cucherousset, Bouletreau, Azemar, Compin, Guillaume & Santoul. 2012. ‘‘Freshwater Killer Whales’’: Beaching Behavior of an Alien Fish to Hunt Land Birds. PLOS ONEhttp://dx.doi.org/10.1371/journal.pone.0050840
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