Roosts of northern long-eared myotis (Myotis septentrionalis) at the western edge of the Great Plains.

ANDERSEN, BRETT R.; GELUSO, KEITH

The northern long-eared myotis (Myotis septentrionalis) is a forest-obligate, tree-roosting bat of the United States and Canada. Most prior studies on roost characteristics were conducted in contiguous forested habitats of eastern North America, where roosting opportunities are potentially numerous. At the western end of its distribution in the Great Plains, M. septentrionalis inhabits narrow, forested riparian waterways. Because these ribbons of forest differ from habitats farther east, roost selection by M. septentrionalis at the western edge of its distribution might differ and affect management practices in the region. Moreover, M. septentrionalis is imperiled by a deadly fungal pathogen, Pseudogymnoascus destructans, the causative agent of white-nose syndrome. Additionally, declining species tend to persist along the periphery of distributional ranges. In northwestern Nebraska, the Pine Ridge region is a landscape characterized by pine-dominated rocky escarpments and represents the westernmost distribution of M. septentrionalis in the state. In this study, we identified roosts for 21 M. septentrionalis, mainly lactating females, during the summers of 2015 and 2016. Bats were located roosting in live trees, snags, and fallen logs, as well as in a wooden fence post. Roost trees varied greatly in height (5.0-27.2 m) and diameter (18.1-114.3 cm), but all roost structures possessed cracks, holes, exfoliating bark, or a combination of these small retreats. Despite their prevalence in the study region, ponderosa pines (Pinus ponderosa) surrounding small watercourses were not typically used as roosts, with M. septentrionalis regularly roosting in deciduous trees along watercourses. Individuals switched roosts frequently, but subsequent roosts were typically in close proximity to one another. The high proportion of live trees used was a major difference in roost characteristics compared to other studies farther east, where roosts primarily occur in snags. Scattered deciduous trees in narrow riparian corridors were best described as open-canopy woodlands, which differs from use of closed-canopy forests in eastern parts of the species' distribution. Our data on roost characteristics in an open woodland habitat for this species, which is a previously undescribed habitat type for M. septentrionalis, will assist in regional management for this federally threatened bat, as some aspects of roost selection appear to be site-specific across its distribution.

Western North American Naturalist, 2022, Vol 82, Issue 3, p586

1527-0904

Academic Journal

10.3398/064.082.0313