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The moon and bat hunger

Ruestz / Wikimedia Commons Moonlight intensity did not change the foraging activity of four of the five bat species studiedRuestz / Wikimedia Commons

On moonlit nights in the tropics, insect-eating bats are thought to decrease their foraging activity, according to a well-known hypothesis. Reduced foraging is likely a response to the fact that fewer insects are present on bright nights, and also to an increased risk that the bats would become easy targets for their predators in a more well-lit environment. One study, however, tested the behavioral association of these flying mammals with moonlight intensity. Over a 53-day period, biologists from the National Institute for Research on the Amazon (INPA) monitored the feeding habits of five different bat species in the Adolpho Ducke Forest Reserve north of the city of Manaus (Mammalian Biology – Zeitschrift für Säugetierkunde, November 11, 2016). Only one species, Myotis riparius, reduced its foraging for insects in relation to the Moon. Two species, Cormura brevirostris and Saccopteryx bilineata, did not change their foraging habits. The other two, Pteronotus parnellii and Saccopteryx leptura, even stepped up their feeding activity on brighter nights. Using sound recorders, the researchers recorded bat activity at 10 different spots in the reserve from January to May 2013, during the rainy season. A total of 636 hours of bat activity were monitored, from 18:00 to 06:00 in each case. At each selected location, the animals’ movements were monitored for four to six consecutive nights.