Artificial roosts designed to attract bats have been used to increase populations, aid seed dispersal, and control insects. More important from a conservation perspective, artificial roosts provide habitat where natural roosts have been lost. Although artificial roosts have been widely used, much of the information on species that use artificial roosts, roost design, and placement is anecdotal and poorly reported. We reviewed the existing literature on artificial roosts to summarize current research and inform research and management decisions. From 47 publications and reports, we identified 48 types of structures used by 59 species. Roosts were constructed from wood (66.7%), concrete (8.3%), or other materials (25.0%) and varied in size and shape from small-volume wood boxes (0.002 m 3 ) to large (6 m tall) free-standing structures. Variables most often considered in the context of attracting bats were aspect, substrate, and mount location; few studies measured height or microclimate. Colonization rates ranged from 7% to 100%. Bats commonly used structures as solitary (21 species) or social (breeding or maternity; 21 species) roosts. Most species documented to use artificial roosts are vespertilionids (73%), have the International Union for Conservation of Nature's designation of least concern (93%), and roost in tree cavities or buildings. Three species are designated as endangered (Myotis sodalis) or near threatened (M. bechsteinii, M. dasycneme). Artificial roosts should be constructed and installed to mimic natural roosts, emphasize requirements of target species, and exclude non-target species. Monitoring species composition and identifying effects of roost density will help determine conservation impacts of artificial roosts. Ó 2014 The Wildlife Society.

Conservation efforts for tree-and snag-roosting bats are challenging because roost sites are difficult and costly to locate. We assessed the ability of scent detection dogs to locate bat roosts using controlled field experiments conducted at 2 sites in northern Arizona, USA, during July and August of 2007, with small bags of bat guano and known bat roosts. Scent detection dogs correctly detected 79% of guano bags and 29% of known bat roosts; but, when searching during shorter time periods for roosts only, dogs correctly detected 77% of known roosts. Factors affecting detection of guano bags included bag height and mass. Factors affecting detection of roosts included height, size of the bat colony, and air temperature. Rest breaks and competition between dogs apparently increased their success rate in finding roosts. Using a scent detection dog to locate roosts was similar in cost to radiotelemetry; however, the use of a scent detection dog was less invasive because the use of dogs precluded the need to capture and radiotag bats. Important considerations influencing the efficacy of using scent detection dogs include training and transportation costs, and skill level of dog handlers. Although some factors limit the ability of scent detection dogs to accurately locate roosts, dogs in our study approximated the roost location to within a 30-m radius, which may be sufficient to protect these areas during management activities. If managers have the ability within an area to retain all large-diameter snags that have bat roost characteristics, then scent detection dogs will likely not provide adequate added value to warrant their survey costs. However, scent dogs could be important for locating roosts of species that are imperiled or of conservation concern. Ó 2015 The Wildlife Society.

Bats use large (69 cm mean diameter) ponderosa pine (Pinus ponderosa) snags for maternity roosts in northern Arizona. Anthropogenic causes have altered forest structure, decreasing density of large snags. To examine use of artificial roosts for bats in these forests, we selected 26 sites and 2 treatments (clustered, single) using 1 type of roost (resin or wood) per site. At each site, we installed 4 roosts on ponderosa pine trees with a cluster of 3 roosts (south-, east-, or west-facing; <20 m apart) and a single roost (south-facing) 250-350 m away. We checked roosts every 2 weeks for use (guano or bats) and monitored internal temperatures every 2 hours from May through September in 2009 and 2010. Bats used 52% of roosts (19 roosts in 2009, 49 in 2010) at least once and colonized resin roosts sooner than wood roosts. Sites with clustered resin roosts were used more than single roosts. Bats used south-and east-facing resin roosts more and these had warmer average temperatures than west-facing roosts. We captured 47 bats of 5 species using artificial roosts. We only captured male bats from roosts in 2009, juveniles and females were also captured in 2010 but no maternity roosts were documented. We recommend that resin roosts placed in clusters on live trees be used to supplement natural roosts in ponderosa pine forests. Because use increased with time we suspect artificial roosts may be used for several years before establishment of maternity colonies. Artificial roosts require annual maintenance (e.g., waterproofing) to maintain function and can be expensive to install and maintain. ß