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Conserving trees for endangered bats

Winter and summer roosting ecology

wearing a glove and holding a bat
New research highlights forest management practices that can provide year-round habitat for tricolored bats and other species. Photo by Enwebb, courtesy of Wikimedia Commons.

Tricolored bats (Perimyotis subflavus) in South Carolina are threatened by habitat loss and white-nose syndrome. New research shows where they roost during winter, and where they and northern yellow bats (Lasiurus intermedius) roost in summer. Northern yellow bats are considered a species a special concern in South Carolina.

USDA Forest Service scientist Susan Loeb contributed to both studies, along with Clemson University graduate students Blaise Newman and Kyle Shute and their professor, David Jachowski.

In summer, tricolored bats roosted in hardwood trees thick with Spanish moss (Tillandsia usneoides). The bats roost in moss and clumps of dead foliage. Northern yellow bats also roosted in Spanish moss in water tupelos (Nyssa aquatica) and oak (Quercus) trees, or in dead palm fronds in cabbage palm trees (Sabal palmetto). The results suggest that conserving forests where such trees are found would benefit both species.

Winter is when bats can be infected with the fungus that causes white-nose syndrome. The fungus thrives in cool, moist caves where bats hibernate. But in places without caves, bats spend the winter under bridges or in tree leaves or hollows.

The researchers discovered that bats prefer:

  • Low-decay trees near streams,
  • Areas where the forest canopy is closed and tree hollows are abundant, and
  • Hardwood forests – bats avoided pine forests.

Bridges were warmer and less humid than tree cavities, so bats used bridges on colder days.

Roost temperatures favored fungal growth on some days but not consistently. Access to multiple roost microclimates might help tricolored bats avoid white-nose syndrome.

Forest management practices that retain trees near streams and foster cavity formation in hardwood forests likely will benefit this species during winter.

Read the studies in the Journal of Mammalogy and Southeastern Naturalist. For more information, email Susan Loeb at