Systematic Review of the Roost-Site Characteristics of North American Forest Bats: Implications for Conservation

Abstract

Continued declines in North American bat populations can be largely attributed to habitat loss, disease, and wind turbines. These declines can be partially mitigated through actions that boost reproductive success; therefore, management aimed at promoting availability of high-quality roosting habitat is an important conservation goal. Following the principles of the umbrella species concept, if co-occurring species share similar roost-tree preferences, then management practices targeting one species may confer conservation benefits to another. We conducted a systematic review of roost-site characteristics of thirteen species inhabiting eastern temperate forests to: (1) synthesize existing knowledge across species; (2) assess niche overlap among co-occurring species; and (3) evaluate the potential for currently protected species to serve as conservation umbrellas. We performed multivariate ordination techniques to group species based on the seven most-reported roost-site characteristics, including tree species, diameter at breast height, tree health, roost type, tree height, canopy closure, and roost height. Species sorted into three roosting guilds: (1) southern wetland inhabitants; (2) foliage specialists; and (3) dead tree generalists. Myotis septentrionalis and Perimyotis subflavus had significant roost-niche overlap with five and four other species respectively, and their existing protections make them suitable umbrellas for other bats in the North American eastern temperate forests.

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

“…At the landscape scale, our findings were generally consistent with individual tree-scale results (Tables 1 and 2). We found that canopy density had the highest relative importance, whereas the total amount of forest cover was not significant, which was consistent with the results from a metanalysis on tree roost characteristics at the landscape scale (Drake et al , 2020). Evening bats choosing low canopy density at the landscape scale reflected that roosts should be easy to access and receive considerable solar radiation for additional warmth (Lausen and Barclay, 2003; Russo et al ., 2004; Klug et al ., 2012; Fagan et al ., 2018).…”

Improving the science and practice of using artificial roosts for bats

“…Although there is much variability in artificial roost dimensions, many designs mimicking natural roosts are ≤30‐cm tall (Crawford & O'Keefe, 2021a; Mering & Chambers, 2014; Rueegger, 2016) and are mounted 3−6 m aboveground (Goldingay & Stevens, 2009; Mering & Chambers, 2014). Natural roost entrances could be more difficult for terrestrial predators to detect if they are higher (e.g., average 8.8 m for 13 tree‐roosting bats in North America [Drake et al., 2020]). Although bats in tree cavities may access roosts from entrances near the ground, such species may select roosts with features that allow them to evade predators (e.g., smooth walls and ample flight space [Clement & Castleberry, 2013]).…”

Species‐specific responses to white‐nose syndrome in the Great Lakes region

“…For example, prior to pups becoming volant, female bats may forage closer to the roost site in order to care for young during lactation (Henry et al, 2002 ). Because roosts are typically located in forests (Drake et al, 2020 ), we predicted that, in open habitat, we would detect less bat activity before pup volancy than after pup volancy (Table 1 ). However, some bat species are primarily open space foragers (Fenton, 1990 ), so this seasonal effect may not hold true for all species.…”

“…Because roosts are typically located in forests (Drake et al, 2020), we predicted that, in open habitat, we would detect less bat activity before pup volancy than after pup volancy (Table 1). However, some bat species are primarily open space foragers (Fenton, 1990), so this seasonal effect may not hold true for all species.…”