Ecology and Vulnerability

Northern Long-eared Bat

Background
The northern long-eared bat, also commonly called the northern myotis, is found in Canada (from British Columbia to southern Quebec and Newfoundland) and the US (its range extends south to Oklahoma and east to South Carolina)^1,2.  Northern long-eared bats eat insects in the forest interior^3,4.  Bats begin to emerge from hibernation in April and May⁵ in northern areas and as early as March in southern areas¹.  During summer, northern long-eared bats can be found in trees during the day. They leave their resting trees to feed immediately after sunset and return to rest again immediately before sunrise^4,6.

Previously, this species was frequently seen in the northeastern US.  More recently, however, many bats have died as a result of a fungus that causes white nose disease⁷.  This disease is currently the greatest cause of death in wintering northern long-eared bats⁵.  In 2013 and 2014, surveys of known hibernation sites in Massachusetts found zero or one northern long-eared bat per site, much lower than is considered normal⁷.  In 2015, the US Fish and Wildlife Service labeled the northern long-eared bat “threatened” under the Endangered Species Act⁷.

Climate Impacts
Bats must store enough energy reserves over the summer to enable them to survive winter hibernation⁸.  Changes in precipitation and temperature are likely to have effects on the availability of the insects they eat and thus on their stored energy reserves⁹.  Additionally, it is possible that warmer temperatures could cause bats to wake up from hibernation more often, which takes more energy⁹.  Moreover, stored energy reserves are depleted at a rate that is dependent on the temperature of the hibernaculum (shelter where they hibernate), with temperatures above or below 2°C/36°F increasing the rate of depletion⁸.  On the other hand, a longer growing season is likely to reduce the length of time that they hibernate. 

It is unclear how these climate change effects will interact to influence bats.  However, models based on energy needs related to hibernation conditions correctly predicted the distribution of the little brown bat in Canada (a northward range shift over the next century)⁸.  Based on these models, similar range shifts are anticipated for other bat species, including the northern long-eared bat.