Automated entrance monitoring to investigate honey bee foraging trips using open-source wireless platform and fiducial tags

Honey bee foraging is a complex behavior because it involves tens of thousands of organisms making decisions about where to collect pollen and nectar based on the quality of resources and the distance to flowers. Studying this aspect of their biology is possible through direct observations but the large number of individuals involved in this behavior makes the implementation of technologies ideal to scale up this type of study. Consequently, there is a need for instruments that can facilitate accurate assessments of honey bee foraging at the colony level. To address this need, this work aimed to develop an automated imaging system for monitoring the in-and-out activity of honey bee foragers as they walk through a customized entrance with a camera sensor at the hive entrance. We used AprilTags attached to each bee's thorax to provide unique identification numbers that allowed the system to track in-and-out events throughout the foraging season of the colony. Our design relies on low-cost Raspberry Pi computers and cameras, along with commercially off-the-shelf components, making it easily reproducible with the open-source documentation provided. We successfully deployed and evaluated our system in six locations, demonstrating consistent results. In this paper, we present the details about the development of the system, data collected from multiple colonies, and post-processing analysis from one of our apiaries. Our results highlight the system's effectiveness in monitoring honey bee trips, capturing various behaviors associate with their activities outside the colony, which lay the groundwork for future estimations of foraging distances.