FORAGING BY RED BATS (LASIURUS-BOREALIS) - DO INTRASPECIFIC CHASES MEAN TERRITORIALITY

Thirteen individually marked Lasiurus borealis concentrated their foraging around lights where insect densities were higher than in surrounding dark areas. The marked bats foraged for an average of 113.1 min per night, attacked an insect every 30 s, and captured, on average, 40% of the insects they attacked. This translated to a nightly food consumption of 6.2 g of insects, or 42% of the bats' body mass. The bats selected large (body length > 10 mm) moths significantly more often than predicted by their availability, but the foraging activity of the bats did not significantly deplete the patches of prey. Individual L. borealis preferred certain lights within the feeding site and intraspecific chases were common, but there was no significant relationship between prey density and the incidence of chases, and the chases did not result in individuals being excluded from the feeding areas. Our data support the hypothesis that individual L. borealis eavesdrop on the echolocation calls of conspecifics to identify the presence of prey and that conspecific chases at feeding sites are not evidence of territorial behaviour.