European Wels catfish (*Silurus glanis*) in the Tarn River at Albi, France, have developed a unique hunting behavior: intentionally beaching themselves to capture pigeons on the riverbank. Documented by researchers from the Laboratoire Écologie fonctionnelle et Développement, this behavior mirrors the terrestrial hunting tactics of orcas, marking a rare instance of freshwater fish adapting to land-based prey through intentional stranding.
Why do Wels catfish hunt pigeons?
Wels catfish in the Tarn River have evolved to target pigeons because of their high caloric density and availability. According to researchers led by Julien Cucherousset, isotope analysis of fish tissues reveals that for some individuals, pigeons account for up to 80% of their total diet. This is not a universal trait among the species; while the population of Wels catfish in the area can reach lengths of 2.74 meters, only specific individuals have specialized in this “vocation.” The catfish identify their prey not by sight, but by detecting vibrations produced by the birds’ movements in the water, utilizing their six hypersensitive barbills and lateral lines.
The Wels catfish is the largest freshwater fish in Europe. While they are native to Eastern Europe and Asia, their introduction to the Tarn in 1983 has led to rapid colonization across Western Europe due to their high physiological plasticity.
How does the “freshwater orca” hunting technique work?
The hunting sequence is a high-speed maneuver that typically lasts between one and four seconds. As documented in the journal PLoS ONE, the catfish propel themselves onto the riverbank, capturing the bird before using a violent wriggling motion to return to the water. Field observations conducted from June to October 2011 involved 45 recorded stranding sequences, with a 28% success rate in capturing prey. This efficiency rivals that of many apex terrestrial predators, according to the research team.
Is this behavior a sign of species evolution?
This hunting strategy is an example of behavioral plasticity rather than an inherited instinct. Frédéric Santoul of the Laboratoire Écologie fonctionnelle et Développement notes that this behavior has not been observed in the species’ native range, suggesting it is a locally invented technique. Because the behavior is transmitted or reinvented within the specific population in Albi, it serves as a case study for how invasive species adapt to new environments. Scientists are currently investigating whether this specialized diet is a response to a decline in native aquatic prey or simply an opportunistic expansion of the catfish’s ecological niche.
Comparison: Wels Catfish vs. Other Predators
| Feature | Wels Catfish (Tarn) | Orca (Marine) |
|---|---|---|
| Primary Hunting Method | Intentional stranding | Intentional stranding |
| Target Prey | Pigeons | Seals/Sea Lions |
Frequently Asked Questions
- Are these catfish dangerous to humans? No, current research focuses exclusively on their predation of birds and small mammals; there is no evidence of human-directed aggression.
- Is this behavior happening in other rivers? While Wels catfish elsewhere in France may occasionally target waterbirds like cormorants or ducks, the specific, high-frequency stranding behavior seen in Albi is unique to that population.
- Why don’t the pigeons learn to avoid the bank? Researchers have observed that the hunting occurs during specific times of the year, and the pigeons remain largely unaware of the threat posed by the submerged predators.
If you are interested in wildlife observation, the best time to witness unique predator-prey dynamics is during seasonal migration or breeding periods when prey behavior becomes predictable. Always maintain a safe distance to avoid disrupting natural patterns.
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