Natural Resources Research Institute Technical Report

Although long thought to exist throughout the forested region of Minnesota, occurrence records for northern long-eared bats (Myotis septentrionalis) were historically based on winter hibernacula records and sporadic summer observations. The ability to record and identify bats by their echolocation calls allowed scientists to more systematically survey for bats in Minnesota beginning in the 2000s; however, these data were not compiled in a central database. With the arrival of whitenose syndrome in Minnesota and the federal listing of the northern long-eared bat in 2015 as threatened under the Endangered Species Act, the need for a more detailed and current distribution map for this species was evident. In this report, we summarize the occurrence records for northern long-eared bats based on specimens collected, existing acoustic survey data from various sources collected prior to 2015, and acoustic survey data collected from 2015 to 2017. Northern long-eared bats do appear to be distributed throughout the forested region of Minnesota. Presence has been documented in the northern half of the state, surrounding the Twin Cities metropolitan area, and in the southeast corner of the state. Detection of the northern long-eared bat in almost every attempt suggests that the species is also present in unsurveyed regions of the forested regions of the state, although it is less common than the little brown bat (M. lucifugus), especially after white-nose syndrome has led to mortalities in Minnesota