Evening Bats Captured in a Managed Wildlife Refuge Used Trees in a Human-Dominated Landscape as Maternity Roosts

Abstract

Similar to many chiropteran species, pregnant and lactating evening bats Nycticeius humeralis form maternity colonies to bear and raise their pups. Although evening bat maternity roosts have been studied in other locations, knowledge gaps exist regarding maternity roost site selection on the Gulf Coast of Texas, United States; thus, our objective was to quantify maternity roost characteristics of evening bats in this region. We radiotracked 11 female and subadult evening bats to nine roosts during June and July 2018 and 2019 captured in San Bernard Wildlife Refuge (SBNWR). No transmittered bats roosted in SBNWR and instead all roosts were located 3.6–4.5 km from the same capture site, within an 81-ha residential area of a 5,496-ha city. Five of the nine roosts were in tall, live, live oak trees Quercus virginana and one roost was in a residential home. Colony size of bats occupying the roosts ranged from 16 to 500+ bats. All evening bats, including those on properties we were denied access to, stayed in roosts for the full life of the transmitter (five–21 days) and no roost switching occurred. Although evening bats used SBNWR, potentially for foraging, results suggest trees in the residential area provided suitable maternity roost characteristics. A lack of roost switching may suggest a lack of available roost trees in SBNWR and residential areas or the selected roost trees were high quality. We recommend future studies increase sample sizes of evening bat roosts on the Gulf Coast of Texas, as well as assessing roost site selection of evening bats and monitoring bachelor colony and evening bat winter roost ecology.

Selection of Maternity Roosts by Evening Bats (Nycticeius humeralis) in a Riparian Forest at the Northern Edge of Their Range

“…The evening bat ( Nycticeius humeralis ) is a medium-sized vespertilionid that is widely distributed over a span of 17 degrees of latitude, from the Gulf of Mexico northward to the Great Lakes of North America (Watkins, 1972). Roosts for the evening bat typically are structures associated with a tree, such as exfoliating bark, cavities, or crevices (Menzel et al , 2001; Boyles and Robbins, 2006; Perry and Thill, 2008), although roosting in manmade structures (e.g., buildings) and bird boxes also occurs (Watkins, 1972; Whitaker et al , 2006; Li and Wilkins, 2015; Rolland et al ., 2022; Rogers et al , 2023).…”