Scientists use a variety of methods to monitor wildlife populations, including listening for their sounds. This can be done through the use of acoustic monitoring devices, which can record sounds over a long period of time. Scientists can then analyze these recordings to identify different species of animals, as well as their abundance and activity patterns. Acoustic monitoring can be used to track changes in wildlife populations over time, as well as to identify potential threats to these populations. In addition to acoustic monitoring, scientists also use other methods to monitor wildlife populations, such as camera traps, GPS tracking, and field surveys.