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

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.

Implementing and Assessing the Efficacy of the North American Bat Monitoring Program

Bats are under threat from habitat loss, energy development, and the disease white-nose syndrome; therefore, an efficient and effective means to monitor bat populations is needed. The North American Bat Monitoring Program (NABat) was initiated in 2015 to provide standardized, large-scale monitoring to benefit bat biologists, managers, and policy makers. Given the recency of this program, our first objective was to determine the efficacy of implementing NABat. Further, because the probability of detecting a bat varies among species and survey conditions, our second objective was to determine factors affecting detection probabilities of bats using NABat acoustic surveys. We conducted surveys across South Carolina from mid-May through July 2015 and 2016. To determine efficacy of NABat, we compared species detections with historical known distributions and predicted distributions based on environmental occupancy models. To determine factors that affected detection probability, we evaluated support for predictive detection models for each species or species grouping. In general, we found that predicted distributions closely matched known distributions. However, we detected some species in ≤50% of cells within their ranges and others outside their ranges, suggesting NABat may also reveal new information about species distributions. Most species had higher detection probabilities at stationary points than mobile transects, but the influence of interrupted surveys, environmental conditions (e.g., temperature, rainfall, and wind) and habitat conditions often varied among species. Overall, our results suggest NABat is an effective and efficient method for monitoring many bat species, but we suggest that future efforts account for species-specific biological and behavioral characteristics influencing detection probability.

Advances in population ecology and species interactions in mammals

The study of mammals has promoted the development and testing of many ideas in contemporary ecology. Here we address recent developments in foraging and habitat selection, source–sink dynamics, competition (both within and between species), population cycles, predation (including apparent competition), mutualism, and biological invasions. Because mammals are appealing to the public, ecological insight gleaned from the study of mammals has disproportionate potential in educating the public about ecological principles and their application to wise management. Mammals have been central to many computational and statistical developments in recent years, including refinements to traditional approaches and metrics (e.g., capture-recapture) as well as advancements of novel and developing fields (e.g., spatial capture-recapture, occupancy modeling, integrated population models). The study of mammals also poses challenges in terms of fully characterizing dynamics in natural conditions. Ongoing climate change threatens to affect global ecosystems, and mammals provide visible and charismatic subjects for research on local and regional effects of such change as well as predictive modeling of the long-term effects on ecosystem function and stability. Although much remains to be done, the population ecology of mammals continues to be a vibrant and rapidly developing field. We anticipate that the next quarter century will prove as exciting and productive for the study of mammals as has the recent one.