Date of Award

2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biology

Abstract

Bats that roost in cavities and crevices are vulnerable to deforestation and habitat loss. Bat boxes can serve as alternate roosts for tree-dependent bat species, but we know little about how box design affects internal microclimate. If a box gets too hot (> 45°C), it can become an ecological trap. We assessed microclimate in 20 different box designs, using data loggers to measure internal temperatures in each box installed at a 20 ha site in Vigo County, Indiana (20 May–15 September 2018). We evaluated maximum (T max ), minimum (T min ), stability, and instantaneous temperature ranges and proportion of suitable space. The average temperature across all boxes was 25.9°C (range 25.1–26.8°C). Maximum and minimum temperatures recorded by data loggers were 54°C and 11°C, respectively. Changes to box height, which also increased volume, produced the greatest differences in T max , T min , and instantaneous temperature ranges. The short box was cooler and more stable than longer boxes, but longer boxes offered the greatest instantaneous range of temperatures. Slight modifications, like removing vents and adding a chimney dramatically altered box temperatures. Major alterations, like adding internal or external water chambers, stabilized temperatures, but further testing of these designs in more extreme weather conditions is required. Also, studies should examine metabolic heat production of bats, which may be retained more in some designs than others. Based on this study, we recommend careful consideration of bat box designs, as the top-most layer of many designs can reach lethal temperatures. Thus, usable space within a box may be restricted by high temperatures.

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