Indiana Bat - Food Habits

Food Habits

Indiana bats feed exclusively on terrestrial and aquatic flying insects. The most common prey items taken by Indiana bats are moths (Lepidoptera), beetles (Coleoptera), and mosquitoes and midges (Diptera). Selection of prey depends largely on availability in the foraging habitat with diet varying seasonally, by reproductive status of females, and from night to night. In southern Michigan, Indiana bats primarily ate caddisflies (Trichoptera) and bees, wasps, and ants (Hymenoptera), in addition to the more common prey previously listed. In the Ozarks of southern Missouri, the bats also primarily ate bees, wasps, ants, moths, and beetles as well as leafhoppers (Homoptera), although diet did vary throughout the summer. Bats in Indiana were found to prefer beetles, moths, mosquitoes, midges, leafhoppers, and wasps. Other arthropod groups which are consumed by Indiana bats in very limited quantities are lacewings (Neuroptera), spiders (Araneae), stoneflies (Plecoptera), mayflies (Ephemeroptera), mites and ticks (Acari), and lice (Phthiraptera).

In addition to differences in diet, variation in foraging behaviors have been documented. For instance, the distance that an individual Indiana bat travels between a day roost and a nightly foraging range can vary. Garner and Gardner discovered that Indiana bats traveled up to 1.6 miles (2.6 km) from their day roosts to their foraging sites in Illinois. Similarly, bats traveled up to 1.5 miles (2.4 km) to forage in Kentucky. In Michigan, female bats traveled as far as 2.6 miles (4.2 km) to reach foraging areas with an average of 1.5 miles (2.4 km).

Several studies have documented similarities in how foraging habitats are actually utilized by Indiana bats. Humphrey and others found Indiana bats in Indiana were foraging around the canopy, which was 7 to 98 feet (2–30 m) above ground. LaVal and others, whose study was also conducted in Missouri, found that a female bat foraged 7 to 33 feet (2–10 m) above a river. In the same study, a male Indiana bat was observed flying in an elliptical pattern among trees at 10 to 33 feet (3–10 m) above the ground under the canopy of dense forests. In addition, bats were observed foraging at canopy height in Virginia.

Differences in the extent of foraging ranges have also been noted. Bats from the same colony foraged in different areas at least some of the time. Humphrey and others reported that the average foraging area for female bats in Indiana was 843 acres (341 ha), but the foraging area for males averaged 6,837 acres (2,767 ha). Hobson and Holland reported a male bat utilizing a foraging area of 1,544 acres (625 ha) in Virginia. In Illinois, however, the foraging ranges were much smaller at an average of 625 acres (253 ha) for adult females, 141 acres (57 ha) for adult males, 91 acres (37 ha) for juvenile females, and only 69 acres (28 ha) for juvenile males. Foraging areas utilized by Indiana bats in Indiana increased throughout the summer season, but only averaged 11.2 acres (4.54 ha) in mid-summer.