Use of artificial roosts by forest-dwelling bats in northern Arizona

Forest-dwelling bats often use snags and live trees as maternity and bachelor roost sites. These roost sites can be destroyed or altered by natural events (e.g., wildfire) or forest management activities (e.g., prescribed fire, thinning, harvesting). To determine whether artificial roost structures could supplement natural roost sites, we tested 2 types of artificial structures for use by bats: resin (n= 10) and wood (n= 10) roosts. Artificial roosts were placed on snags in 6 ponderosa pine (Pinus ponderosa) stands and compared with use of nearby natural roost snags (n= 10). We monitored the 3 roost types (resin, wood, natural) approximately every 2 weeks for use by bats for 2 summers (1999 and 2000). Over the 2-yr period, bats used 17 of 20 artificial roosts (8 resin and 9 wood), using both artificial roost types in about equal proportions. Bats used 5 of the 10 natural snags monitored. Resin roosts were camouflaged to match tree bark, have a >20-year lifespan, and cost US $42 each after construction of a $250 mold. They can be designed to resemble any tree species. Wood roosts cost about $5 each, were more visible, and likely have a shorter lifespan than resin roosts. Both roost types might require some annual maintenance (recaulking tops and edges). Maintaining and managing for natural roosts should be a priority for resource managers since artificial roosts might not provide the same microclimate as natural roosts. However, artificial roosts might be useful temporary habitat under site-specific conditions. Artificial roosts could also be useful as research tools.