Small Mammal Biologist, Alyssa Bennett, recently visited the NorthWoods Stewardship Center to talk about the nine different bat species found in Vermont, their habitat requirements, and some ways that landowners and natural resource professionals may be able to better manage Vermont forests for bats. Many of our bat species are currently listed as threatened or endangered, with white-nose syndrome negatively affecting cave-dwelling species. Forest management for bats should be focused around three basic habitat needs: roosting areas, foraging sites, and fresh water sources.
Bats often roost in dead and dying trees (snags). They can especially be found roosting beneath loose bark, in tree cavities, or in tree crevices. Bats may also roost in sites located in caves, mines, and human-made structures such as buildings, bridges, and culverts. In Vermont, big brown bats (Eptesicus fuscus) and little brown bats (Myotis lucifugus) are commonly known as “house bats” since they have adapted well to using human-made structures such as older and abandoned houses, sheds, and barns as roost sites.
Bats that roost in living or dead trees tend to move frequently between multiple roost sites. Roost switching may be an effort to avoid predators, reduce parasites, or to seek warmer or cooler roosts based on weather conditions. Roost trees are often found along the edges of forests or in open forest stands, where they receive more sunlight and have a less-obstructed flight path. Emphasis should be placed on larger diameter snags since they tend to remain standing, retain bark longer, and support a greater variety of bats and other wildlife than smaller snags.
Vermont bat species forage in forests, along forest edges, over riparian areas (lands that occur along rivers, streams, and other bodies of water), along forest roads and trails, and in small forest openings – both naturally occurring and human-made. Bats feed on a variety of night-flying insects, catching them in the air or picking them off vegetation. Many bats prefer to hunt in small- to medium-sized forest openings or gaps – such as those created by timber harvests or treefall.
Bats need clean, pooled, open bodies of fresh water that are large enough to enable them to scoop water into their mouths while in flight. Forest management practices that eliminate or limit access to water or degrade water quality can negatively affect bats. Forest buffers on rivers and streams and adherence to state Best Management Practices (BMPs) are effective at protecting water quality for forest ponds, vernal pools, wet meadows, and other bodies of water. Riparian areas, such as beaver ponds, are especially important because they provide drinking water, high-quality foraging habitat, and high-quality roosting habitat.
So, what can landowners do to help maintain bat populations in Vermont? They can strive to provide a continuous supply of potential roost trees on their property! These include snags in various stages of deterioration (especially those in early stages of decay), hollow trees, trees with peeling bark, and living trees that may become snags as the forest ages or is subjected to disturbances. Many other species of wildlife that depend on dead and dying trees will also benefit from these management practices. Additionally, forest management practices that create small forest openings (less than 5 acres) may provide foraging areas and enhance roosts located along forest gaps and edges. Smaller harvest areas have greater edge per unit area and promote plant and insect diversity that is beneficial to bats and other wildlife.
Other Resources
VT Fish & Wildlife – About Bats