AgEBB-MU CAFNR Extension

Green Horizons

Volume 20, Number 1
January 2016

Forest landowners play a critical role in stewardship of wildlife resources, including bat species. Almost all North American bats rely on forests to provide the basic components all wildlife require to survive: roosting, feeding and drinking sites. Bats forage along forest edges, over riparian areas, along forest roads and trails and in natural forest gaps or management-created openings. Bats need clean, open bodies of fresh water that are large enough to enable drinking on the wing and without obstructions from vegetation.

Some forest bats roost exclusively in the foliage of living trees; these are often referred to as "tree bats". Other species roost under loose, peeling bark or in crevices of dead or damaged trees. Forest-bats, especially maternity colonies, move frequently between roost trees. This roost switching may be an effort to avoid predators or parasites or to seek a warmer or cooler roost. For snag-roosting bats, switching could also be tied to the temporary nature of dead and dying trees. If a roost tree becomes unstable or falls, the bats will already know of an alternative roost. It is not uncommon for bats to return to the same roost tree or group of trees in the same patch of forest in successive years.

White-nose syndrome (WNS), a recently emerged disease affecting bats that hibernate, is associated with the fungus Pseudogymnoascus destructans. This fungus grows in relatively cold conditions with high humidity, which makes many caves, abandoned mines, and other underground structures optimal growing sites for the disease during winter. Of the six species known to be affected by the deadly bat-disease, the northern long-eared bat (Myotis septentrionalis) is among the hardest hit with reported declines of 98 percent. Given that white-nose syndrome has already spread to 25 of the 39 states where the northern long-eared bat is found, it's clear the future existence of this bat is very much in doubt. Northern long-eared bats were recently listed as threatened under the Endangered Species Act joining Indiana bats (Myotis sodalis) and gray bats (Myotis grisescens) (both ESA listed Endangered) under Federal protection. The northern long-eared bat is about three-to-four inches long with a nine-to-ten inch wing span. As its name suggests, it is distinguished by its long ears, relative to other bats in genus Myotis. In summer, these bats roost under bark and in crevices and cavities of living or dead trees that are often larger than the average diameter trees. Maternity roost sites must provide warm microclimates that maximize growth rate of the young.

Bats play an essential role in maintaining forest health by consuming their body weight in insects each night. As major predators of defoliating forest and agricultural insects, bats provide an estimated $23 billion/year benefit to agriculture. Forest-management practices such as harvesting or prescribed burning can have positive or negative effects on bats by altering the distribution and abundance of living and dead trees used for roosting or the number of forest openings and edge habitat used for foraging. Forests can be successfully managed for both wood products and bat habitat, as long as adequate roosts, foraging habitat and water sources are provided across the landscape.

Forest-management is a wise investment in America's forests and management practices that improve forest health and productivity can also maintain and enhance habitat for these fascinating and beneficial animals.

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