Response of a native endangered axolotl, Ambystoma mexicanum (Amphibia), to exotic fish predator

The axolotl (Ambystoma mexicanum) is a critically endangered and threatened species endemic of the Central Valley of Mexico. The population of this neotenic amphibian has declined in recent years as a result of habitat destruction, polluted waters, and the introduction of exotic species such as tilapia. We evaluated the antipredator response of predator-na < ve axolotls to visual and chemical cues of the Nile tilapia (Oreochromis niloticus) and its foraging consequences. Axolotls decreased their activity and increased their use of refuge in the presence of combined chemical and visual cues from the predator. The axolotls seem to use their vision to confirm the level of risk perceived through chemical signals to modulate their antipredator response accordingly. The axolotls engaged in prey capture at a similar rate independent of the type of predator exposure. However, the efficiency of prey capture decreased in axolotls exposed to the chemical and the combined visual and chemical cues from the tilapia. The foraging costs to the axolotls induced by tilapia can ultimately affect their growth rate and size. The axolotls display antipredator behaviours to reduce the risk of predation by tilapia, which is a primary condition of coexistence with this exotic predator.