Bats and Climate Change

by Scott Bergeson

Project Summary

Figure 1: Majority of Indiana bat suitable habitat will be lost by 2030, as predicted by climate change scenarios (Loeb and Winters. 2012. Ecology and Evolution.)

Figure 1: Majority of Indiana bat suitable habitat will be lost by 2030, as predicted by climate change scenarios (Loeb and Winters. 2012. Ecology and Evolution.)

My project is an attempt to understand the impacts of climate change on Eastern North American bats, specifically the endangered Indiana bat (Myotis sodalis), and how these mammals may be able to avoid these impacts by altering their behavior. While it is believed that all eastern North American bats are in danger of population decline due to the impacts of climate change, it is predicted that these impacts will drive the endangered Indiana bat to close to extinction (Figure 1).

However, these predictions were made without considering the individual behavior of bats. Many researchers believe that organisms may be able to adapt to rapid changes in climate through the flexibility of their traits. For example, an organism may seek shade more frequently when their environment’s average temperature increases. It is possible that Eastern North American bats may be able to avoid the harsh negative impacts of climate change through flexibility in their choice of roost, where they spend most of their daytime hours (Figure 2), and flexibility in the methods they use to maintain their internal body temperatures.

Figure 2: Two roosts used by a Midwestern Indiana bat population, demonstrating the variability in roost characteristics that bats can choose from.

Figure 2: Two roosts used by a Midwestern Indiana bat population, demonstrating the variability in roost characteristics that bats can choose from.

The focus of my project is to investigate the flexibility of these traits within the endangered Indiana bat to determine how they may allow the species to avoid extinction caused by climate change.

Figure 3: An Indiana bat, with a transmitter affixed to its back, about to be released back into the wild.

Figure 3: An Indiana bat, with a transmitter affixed to its back, about to be released back into the wild.

I will use radio signals, produced by small transmitters affixed harmlessly to bats’ backs, to track Indiana bats to their roosts in order to meet my objective (Figure 3). I will then measure and record the body temperatures of these bats through the use of the same transmitters (which are sensitive to temperature) and a series of mathematical equations. I will then use these body temperatures to identify the use of torpor by the bats, which is an energy saving bodily process represented by a large decrease in internal body temperature (Figure 4). Torpor is the daily equivalent of long term hibernation. I will then examine whether the characteristics of the bats’ roosts and the local climate have an effect on the bats’ use of torpor.

Figure 4: Evidence of torpor being used by an adult female Indiana bat within my main study site. Use of torpor is observed when the bat’s skin temperature (a good proxy for body temperature) falls sharply below the bat’s torpor onset threshold. The bat’s skin temperature then closely follows the outside air temperature around the roost.

Figure 4: Evidence of torpor being used by an adult female Indiana bat within my main study site. Use of torpor is observed when the bat’s skin temperature (a good proxy for body temperature) falls sharply below the bat’s torpor onset threshold. The bat’s skin temperature then closely follows the outside air temperature around the roost.

Additionally, I will conduct my project with the help of enthusiastic undergraduate researchers, whom I will advise as they design and conduct their own research projects focused on the topics (Figure 5). I hope to provide these undergraduates the experience and confidence they require to succeed in future scientific careers. I will also present my findings to the public through multiple presentations conducted through Indiana State University’s Center for Bat Research, Outreach, and Conservation. Presentations will include community outreach talks, information tables set-up at multiple community events, field talks in which I will expose the public to natural bat behavior and ecology, and a webpage containing the results of my research hosted on the Center for Bat Research, Outreach, and Conservation’s website.

Please continue to check back for updated results.

Figure 5: Side project related to this bats and climate change project in which undergraduate researcher James Cox is attempting to determine the effectiveness of ambient temperature sensitive transmitters in measuring the internal temperatures of bats’ roosts, a typically difficult type of data to record.

Figure 5: Side project related to this bats and climate change project in which undergraduate researcher James Cox is attempting to determine the effectiveness of ambient temperature sensitive transmitters in measuring the internal temperatures of bats’ roosts, a typically difficult type of data to record.

 Funding provided by the Indiana Space Grant Consortium.