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The availability of suitable roosts is an important factor affecting the viability of bat populations. In Europe and North-America, the installation of artificial roosts is a standard conservation measure to mitigate the loss of tree cavities or crevices at buildings. How quickly artificial roosts, such as bat boxes, are adopted, depends on how easily the bats can find them, and on their suitability for roosting. While there is some information about how the design of bat boxes influences their occupancy, it is unknown to what extent the use of bat boxes depends on their detectability. In this experimental field study, we studied the roost selection behavior of three forest-living bat species. We investigated whether attaching an external echo-reflector to bat boxes influenced the time until the bats discover a box or the total number of discovered boxes, which are proxies for detectability. We also assessed whether this modification improved the occupancy of newly placed boxes, as a proxy for their attractiveness. As a result of a previous study, all studied bat colonies were familiar with the echo-reflector as an indicator for the suitability of bat boxes as a day roost. For each species, we compared between boxes with and without an echo-reflector, the number of boxes discovered, the number of days elapsed until discovery, the number of subsequent visits, and the number of days that each box type was used as day roosts. Myotis bechsteinii and Myotis nattereri discovered, visited and used more unmodified boxes than boxes with echo-reflectors. Plecotus auritus did not show differences in behavior with regard to the box types. Our results show that attaching an echo-reflector to newly placed artificial roosts does not improve their discovery and subsequent occupation, even when bats are already familiar with this cue as an indicator of suitability. We discuss the implication of our findings for bat conservation. [ABSTRACT FROM AUTHOR]

Many terrestrial vertebrate species are exhibiting geographic distribution changes including poleward range limit shifts in response to increases in regional temperature. Bats are a highly mobile taxa capable of rapid responses to changes in abiotic or biotic conditions. In North America, recent extralimital records of the non-hibernating Lasiurus seminolus (Seminole bat) have been attributed to climate change, however such attributions remain speculative and potentially subject to sampling bias in the form of increased recent sampling efforts at latitudes north of the historical range. We used historical occurrence records and simple environmental variables within a Maxent modeling framework to model the historical distribution of suitable areas for this species. We transferred the model using near current environmental conditions and measured the ability of the model to capture the apparent expansion in distribution using recent extralimital occurrence records. Our model transferred well over time concluding that the distribution expansion may be largely attributed to increasing minimum temperatures. We used the model to forecast the expansion in distribution of suitable areas at three 20-year intervals and various climate change scenarios and provide extrapolation risk maps for each scenario. Although increasing temperatures may increase potentially occupiable areas, the species is associated with forests and often roosts in pines (Pinus spp.). This suitable habitat is more limited to the northwest of the species' range, which may constrain the future species expansion despite favorable temperatures. We demonstrated this effect by mapping limiting factors through future climate change scenarios. We discovered a broad shift of effects that constrained the distribution from minimum temperature to an abundance metric of evergreen cover type as time and climate change intensity increased. Although uncertainties exist, we predict further expansion of the Seminole bat widely over the next 60 years across the eastern United States where suitable habitat and climate conditions converge. Our results appear consistent with other bat species showing similar range extensions and in turn provide further evidence that bats may serve as bioindicators of global change. [ABSTRACT FROM AUTHOR]

The article presents a study to estimate the sample sizes necessary for a landscape-scale-mark-recapture-based monitoring program of North American migratory tree bats. The study involved power analyses using a statistical model that allows reencounters of live and dead marked individuals. It finds that increasing recovery of dead marked individuals may be more valuable than increasing capture probability of marked individuals, based on sensitivity analyses.