02 December, 2010

Scorpion eating bats

Even though scorpions are notorious predators with a venomous sting, they also are prey for other predators including several vertebrate predators like reptiles, birds and mammals. Marc Holderied and co-workers have published an interesting study showing how the Hemprich's long-eared bat (Otonycteris hemprichii) prey on scorpions in Israel.

Interestingly, the bats didn't differ between potent species like Leiurus quinquestriatus and more harmless species like Scorpio maurus, and stings didn't change the bat's behavior and caused no sign of poisoning.

Over 70% of the droppings of the gleaning bat Otonycteris hemprichii can contain scorpion fragments. Yet, some scorpions found in its desert habitat possess venom of the highest known toxicity, rendering them a very dangerous prey. In this study, we describe how O. hemprichii catches and handles scorpions, quantify its flight and echolocation behaviour in the field, investigate what sensory modality it uses to detect scorpions, and test whether it selects scorpions according to their size or toxicity. We confirmed that O. hemprichi is a whispering bat (approx. 80 dB peSPL) with short, multi-harmonic calls. In a flight room we also confirmed that O. hemprichii detects scorpions by their walking noises. Amplitudes of such noises were measured and they reach the flying bat at or below the level of echoes of the loess substrate. Bats dropped straight onto moving scorpions and were stung frequently even straight in their face. Stings did not change the bats’ behaviour and caused no signs of poisoning. Scorpions were eaten including poison gland and stinger. Bats showed no preference neither for any of the scorpion species nor their size suggesting they are generalist predators with regard to scorpions.

Holderied M, Korine C, Moritz T. Hemprich's long-eared bat (Otonycteris hemprichii) as a predator of scorpions: whispering echolocation, passive gleaning and prey selection. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2010. Ahead of Print Nov 18. DOI: 10.1007/s00359-010-0608-3. [Subscription required for fulltext]

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