Approaches, challenges and recent advances in automated bee counting devices: A review

For nearly 100 years, electronic bee counters have been developed using various technologies to track the foraging activity of mostly honey bee colonies. These counters should enable remote monitoring of the hives without disturbing natural flight behaviour while generating precise scientific data. However, there are few counters on the market that are able to fulfil this task. One main challenge is the lack of standardised methods to validate a counter's precision, as validation is crucial to categorise and judge the data produced by the counter, especially for scientific purposes. Another challenge is the interpretation of flight data to measure the effects of environmental or anthropogenic sources. Nevertheless, recent developments in the field are promising. This review describes the historic development of automated bee flight measurements and critically compares validation methods to encourage their improvement. To increase the comparability of future analyses of bee counters, current advances in data interpretation are also presented.