Methods for assessing artificial thermal refuges: Spatiotemporal analysis more informative than averages

1: Thermal refuges are widely used by animals of all taxonomic groups and are critical to survival in severe weather. 2: Human activities are reducing the availability of natural refuges; consequently, artificial refuges are used as conservation management tools, particularly for bats. 3: Published box evaluations are generally incomplete, omitting thermal physiology and relevant thermal properties. 4: Here, we compare methods for evaluating the potential utility of bat box designs for bats and present a graphical spatiotemporal method that provides more complete information. 5: For illustration, we compare the original to three modified versions of the "rocket box" style bat box. 6: Box internal temperatures and generalized thermal physiology models are combined in two suitability indices appropriate to the mother, and to pups. 7: Results revealed that daily and seasonal averages of these indices obscured important processes and showed insignificant differences among bat box design modifications. 8: In contrast, graphical analysis highlighted the presence and spatiotemporal structure of significant differences among boxes, which were most evident in sunny weather. 9: Differences among boxes were sensitive to assumptions about bat thermal physiology and behavior. 10: We found that an external water jacket mitigated temperature extremes and extended favorable temperatures into the night, which could enhance pup development while the mothers foraged. 11: Further experiments are needed to evaluate the relation between metabolic heating by box occupants and thermal conditions within bat boxes.