The goal of this research is determining how increased temperatures impact the number of bat calls recorded in Copenhagen, Denmark. In July 2022, Denmark experienced a record-breaking heat wave. I hypothesized that there would be more bat calls in July 2022 than in 2021. I analyzed July 2021 and 2022 calls recorded from a bat detector in a suburban garden and found that there were significantly more calls in 2022 after the heat wave started.