Handling missing data
There were a few instances when recorder failure led to missing data, most notably in the first half of February 2022. Recorder failure was typically caused by low battery voltage and resulted in premature termination of recordings, i.e., files with a duration of less than 29 minutes and 55 seconds. A complete record of all dates and times with missing data can be found in the Supporting Information. When reporting number of vocalizations per hour or per month, the true recording duration was used as the denominator to account for missingness in the time series and variability in the duration of months. Hours with greater than 60% missingness were omitted from the time series.