Little brown bat activity patterns and conservation implications in agricultural landscapes in boreal Yukon, Canada

Agriculture can threaten the persistence of bat populations by removing forests and wetlands and by intensifying production. Both processes are underway in expanding agricultural landscapes of boreal North America. To inform land planning and agricultural practices aimed at maintaining a viable population of the little brown bat (Myotis lucifugus), we assessed the use by bats of human-modified (open fields, forest-field edges, and cleared edges of ponds) and unmodified (forest ponds and forest interior) habitat features in agricultural landscapes in southern Yukon, Canada (60 degrees N-61 degrees N), using acoustic recordings. We summarized bat activity (number of 3-s acoustic files with >= 1 pass/night) and bat feeding (files with > 1 feeding buzz/night) at grouped sets of habitat features (sites) and used generalized linear mixed models to test predictions about relative use of habitats. The active season for bats was late April to early October. Little brown bat feeding was strongly correlated with general activity, but feeding comprised a significantly higher proportion of all activity at forest ponds and forest interiors compared to field edges, open fields, and ponds in fields. Total bat activity was highest at forest ponds, followed by field edges, and substantially less in forest interiors and open fields. Forest ponds were used more than the edges of nearby ponds with some riparian clearing for fields. Bats increased use of forest interiors and decreased use of fields as duration of darkness decreased close to summer solstice. We recommend exclusion of ponds, lakes, and other wetlands from future agricultural land disposition, and retention of a riparian forested buffer of >= 40 m around current water bodies on farms. We also recommend retention of strips or patches of forest bordering fields and connected to riparian areas and to more extensive forests on public lands. A relatively young agricultural landscape can avoid some of the risks of intensive agriculture with proactive planning and stewardship.

Automated summary

Agriculture poses a threat to bat populations by destroying habitats and intensifying production. A study in southern Yukon, Canada, found that little brown bats preferred forest ponds and forest interiors for feeding, while open fields and cleared edges of ponds were less preferred. It is recommended to exclude wetlands from agricultural land disposition and retain forested buffers and patches connecting to riparian areas and larger forests.