Does the barn owl (Tyto alba) selectively predate individual great mouse-eared bats (Myotis myotis)? [Loví sova pálená (Tyto alba) jedince netopýra velkého (Myotis myotis) výběrově?]
Ján Obuch, Klára J. Petrželková, Jan Zukal
There is good evidence that owls prefer to prey on smaller and younger rodents, but nothing is known about possible selective predation on bats. We studied predation on the mouse-eared bat (Myotis myotis) by the barn owl (Tyto alba). A set of skulls of Myotis myotis from pellets of Tyto alba was compared with a control one (samples from museum collection) and it was found out that skulls from owl pellets were smaller. The differences were mainly in lengths of upper and lower toothrow and rostral breadths across upper teeth. Our results indicate that Tyto alba most probably prefer to prey on volant inexperienced yearlings which are easier to catch, whilst reaching almost adult size. Volant yearlings lack flying skills, hey are conspicuous during the emergence and they often concentrate near the roost during their early practice flights, making them more vulnerable to owl predation then adults.