Wednesday, February 14, 2007

Bats Prey On Nocturnally Migrating Songbirds

image Batman & Man-Bat © DC Comics
It was previuosly believed that nocturnally migrating songbirds could stop their anti-predator vigilance at night. A new study shows that the giant noctule bat, Nyctalus lasiopterus, exploits [eats] the billions of Eurasian songbirds when the birds' flight routes converge around the Mediterranean basin, such as the Iberian Peninsula.

They showed that the bats ate only insects in summer, included some songbirds' flesh in their diet during spring, and depended a great deal on passerines during autumn. Moreover, a higher fraction of songbirds' flesh in autumn than in spring was attributed to the more massive passerine migration in autumn, because both parents and offspring migrate then towards their wintering grounds in Africa.

Nyctalus lasiopterus. Credit: Ana Popa-Lisseanu
The ability of giant noctules to prey on the wing upon nocturnally migrating passerines appears unique not only among bats but also within the whole animal kingdom. The unique ecological niche of the giant noctule may in turn explain some of its peculiar natural history traits. First, the species occurs almost exclusively in some restricted parts of the Mediterranean where major streams of migrating birds congregate. Second, it is among the largest Palaeartic bats and even belongs to the heaviest aerial-hunting bats of the world, a prerequisite for subduing prey items as large as passerines. Link: press release

The Noctural Predator In Action:

Bats Conquest of a Formidable Foraging Niche: The Myriads of Nocturnally Migrating Songbirds. 2007. Citation: A.G. P.-Lisseanu et al. PLoS ONE 2(2): e205.