Birds Take A Bat-tering
By Steve Robinson
It seems that bats - those infamous rabies-spreading, insect-eating night-fliers - are not quite as solely insectivorous as we once thought. Scientists from Spain and Switzerland have provided hard evidence that the flying mammals prey on migrating birds as well.
European bats were thought to only consume insects, but laboratory evidence shows that - despite maintaining this facade in the spring - some switch to eating songbirds during the autumn to supplement their diets.
The bats in question, greater noctule bats, are much larger than their avian prey, with a wingspan of about half a metre (18 inches) and it is possible that they have only recently added birds to their menu.
Initial evidence for the claims came from a team of researchers led by Ana Popa-Lisseanu and Carlos Ibanez who discovered bird feathers in the bats’ dropping.
"Every year, approximately five billion passerines (songbirds) cross the Mediterranean basin during their autumn migrations," the team wrote in the journal PLoS One.
"A big proportion of them are small-sized; as an example, more than 90% of migrating passerines mist-netted in the study area have an average body mass of less than 20 g (0.8 ounces). They thus represent a multitude of potential hunting targets for a large bat like [greater noctule bats]."
This is the first and only instance of such bird-munching behaviour in bats, leading scientists to wonder if it is a shift in only one bat population.
"So far, no predator had been reported to exploit this extraordinarily diverse and abundant food reservoir represented by nocturnally migrating passerines," they wrote.
If this trend begins to spread however, a battle for the skies could well result. My money's on the mammals.
Want more? Go to Steve's page. It's full of literary wonder.
European bats were thought to only consume insects, but laboratory evidence shows that - despite maintaining this facade in the spring - some switch to eating songbirds during the autumn to supplement their diets.
The bats in question, greater noctule bats, are much larger than their avian prey, with a wingspan of about half a metre (18 inches) and it is possible that they have only recently added birds to their menu.
Initial evidence for the claims came from a team of researchers led by Ana Popa-Lisseanu and Carlos Ibanez who discovered bird feathers in the bats’ dropping.
"Every year, approximately five billion passerines (songbirds) cross the Mediterranean basin during their autumn migrations," the team wrote in the journal PLoS One.
"A big proportion of them are small-sized; as an example, more than 90% of migrating passerines mist-netted in the study area have an average body mass of less than 20 g (0.8 ounces). They thus represent a multitude of potential hunting targets for a large bat like [greater noctule bats]."
This is the first and only instance of such bird-munching behaviour in bats, leading scientists to wonder if it is a shift in only one bat population.
"So far, no predator had been reported to exploit this extraordinarily diverse and abundant food reservoir represented by nocturnally migrating passerines," they wrote.
If this trend begins to spread however, a battle for the skies could well result. My money's on the mammals.
Want more? Go to Steve's page. It's full of literary wonder.
Image: PLoS ONE
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