Hello list,
The following paper can be downloaded from
http://www.uvm.edu/~bmitchel/Bioacoustics.html
Ahlen, I., H. J. Baagoe, and L. Bach. 2009. Behavior of Scandinavian
bats during migration and foraging at sea. Journal of Mammalogy
90(6):1318-1323.
Abstract:
We studied bats migrating and foraging over the sea by direct
observations and automatic acoustic recording. We recorded 11 species
(of a community of 18 species) flying over the ocean up to 14 km from
the shore. All bats used sonar during migration flights at sea, often
with slightly lower frequencies and longer pulse intervals compared to
those used over land. The altitude used for migration flight was most
often ,10 m above sea level. Bats must use other sensory systems for
long-distance navigation, but they probably use echoes from the water
surface to orient to the immediate surroundings. Both migrant and
resident bats foraged over the sea in areas with an abundance of insects
in the air and crustaceans in the surface waters. When hunting insects
near vertical objects such as lighthouses and wind turbines, bats
rapidly changed altitude, for example, to forage around turbine blades.
The findings illustrate why and how bats might be exposed to additional
mortality by offshore wind power.
<http://www.uvm.edu/%7Ebmitchel/temp/Ahlen%20-%20Bat%20migration%20behavior.pdf>
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