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The purpose of this study was to determine whether canine wear influences the diet of big brown bats (Eptesicus fuscus). We hypothesized that tooth wear reduces the ability to consume hard-bodied insects, such as beetles, and that older E. fuscus (those with worn canines) would thus include fewer beetles in their diet than younger individuals (those with less-worn canines) do. We examined 600 fecal pellets collected from 60 female bats captured at a single maternity colony in southeastern Alberta, Canada. The diets of two groups were similar in composition, despite considerable differences in canine wear. Diets were dominated by beetles (Coleoptera), which accounted for 30 to 40% of the identifiable food items. Younger bats included more beetles in their diet, although the difference was not statistically significant. The results suggest that older bats are still able to use their worn canines to effectively puncture hard exoskeleton, perhaps because of the angular shape of the worn teeth.
Laephotis wintoni is a rare bat and little is known about its biology. We studied this species at Algeria Forestry Station in the Western Cape Province, South Africa. A female caught in November 2002 was pregnant and three females caught in November 2004 were all lactating. The three lactating females were radio tagged and roosted in crevices or narrow fissures in a cliff face above the valley where they foraged. Laephotis wintoni is a small insectivorous bat (body mass, x̄ ± SD = 9.6 ± 0.5 g, n = 4) with low wing loading (7.0 ± 0.7 Nm−2, n = 4), low aspect ratio (5.7 ± 0.5, n = 4), low wingtip shape index (1.2 ± 0.2, n = 4) and long ears (20.9 ± 2.3 mm, n = 2). Its morphology suggests that it is a slow manoeuvrable flyer that can fly close to vegetation, or the ground or over water surfaces. Its relatively pointed wings suggest that it probably does not fly in dense clutter. Furthermore, it combines this wing shape with echolocation calls of relatively low intensity, short duration (2.6 ± 0.8 ms, n = 5), narrow band (13.5 ± 2.9 kHz, n = 5) and surprisingly low peak frequency (22.1 ± 0.6 kHz, n = 5). The latter two parameters make it unlikely that the calls are used to overcome masking effects associated with flying in dense clutter. Instead, we propose that its echolocation calls are adapted to be less audible to tympanate insects. This is supported by the fact its diet is dominated by moths in a habitat where tympanate moths comprise 90% of the moth population.
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