Entrance activity monitors can be grouped by the type of sensor and the variety of activities they can (potentially) monitor. The most broadly capable activity monitors are video-based. There is, however, only one of those on the market, Keltronix’ EyesOnHives, and at the moment it can only monitor the general level of activity at the hive entrance. The second type of entrance activity monitor is audio-based. These are not to be confused with in-hive audio-based monitors. An audio-based entrance activity monitor is available from Arnia. The third type of entrance activity monitor focuses mainly on foraging; it counts the bees entering and exiting the hive. Most bee counters actually impede other entrance board activities so their use is limited. Both commercial and do-it-yourself bee counters are available.
Before opening a hive, experienced beekeepers can discern a lot of information about the state of the colony by observing the activity at the front of a hive and on the landing board. The book, At the Hive Entrance, provides many examples of what we can learn by examining the hive entrance for clues about the health and productivity of the colony inside. We cannot be in the bee yard all the time, however, so the possibilities of an automated entrance monitoring system are enticing. The book, At the Hive Entrance, originally in German, tells you, “How to know what happens inside the hive by observation on the outside”.
At the Hive Entrance; H. Storch. Available online from Amazon.com and others. https://www.amazon.com/At-Hive-Entrance-H-Storch/dp/1502864703
Video-based Activity Monitors
Using video to monitor a hive entrance enables various activities to be recorded such as foraging, drone activity, mating flights, swarming, robbing, absconding, undertaking, and predation by wasps, birds, skunks, and others. Also, capturing video of the hive entrance together with image interpretation software to count bees offers a less-intrusive means of counting foragers. Video-based bee counters overcome the disadvantages of motion-based bee counters which reduce the hive entrance and can interfere with cleaning activities, temperature control, etc. As bees tend to die outside the hive, an excess of departures over arrivals may indicate the presence of other problems.
Keltronix’ EyesOnHives appears to be the first commercially available system that captures video imagery of activity at the hive entrance, analyzes the video automatically, and reports the results on a website where it is accessed by the beekeeper. The software analyzes activity levels rather than counts of forager flights in and out, but this is enough to tell when foragers are flying, how many (in terms of bees/second) are flying, when swarms or orientation flights are taking place, and to distinguish between swarms and orientation flights. Each time there is a significant change in activity, the system records a few seconds of video for the beekeeper to review later. The system also records a time-lapse video of the entire day’s activity.
Video cameras consume significant power, and this system needs a connection to household current, which limits its use to yards with an electrical outlet. Information is transferred from the system to the internet by Wi-Fi, so the yard must also have Wi-Fi access. Users buy the camera system and subscribe to the data analytics service.
Audio-based Activity Monitors
Audio-based entrance activity monitors consume much less power than video-based monitors and can run on small batteries. Like video data, audio data can be interpreted by software to provide beekeepers with reports regarding the status of their colonies. Specifically, the pitch or frequency of bees’ buzzing indicates that bees are either flying or fanning, and the loudness or intensity at these frequencies indicates, roughly, the number of bees engaged in that activity. Besides foraging, other activities cause bees to leave the hive in great numbers, activities such as orientation flights, swarms, absconding, queen mating flights, etc., so these may also be detected by audio-based entrance activity monitors.
Arnia’s audio-based entrance activity monitor is embedded in the small box that contains a processor and transmitter for other sensors. This box is placed at the hive entrance where the microphone can capture landing board activity. The audio activity is analyzed automatically, and sent to the Arnia website where it is accessed by the beekeeper. The software analyzes activity levels rather than counts of forager flights in and out, but this is enough to tell when foragers are flying and to detect periods of heightened activity, such as when swarms or orientation flights are taking place.
The chart below, from Arnia, shows flight and fanning noise at the hive entrance for a two-day period; flight noise in yellow and fanning noise in purple. The fanning noise, with peaks before 6 am and 6 pm is similar both days, while the flight/foraging pattern has a single peak on the first day and a double peak on the second day.
Foragers bring the colony the nectar and pollen it needs, and the third type of entrance activity monitor focuses mainly on foraging, counting bees exiting and entering the hive. These bee counters use mechanical, optical, or electrical field sensors to detect the passage of bees in and out of the hive through small holes which impede other entrance board activities (such as fanning and undertaking), limiting their use to brief periods of time. Both commercial and do-it-yourself bee counters are available.
Commercial bee counters
The Lowland Electronics bee counter has been available for many years.
Do-it-yourself bee counters
HiveTool.org is a site that helps technically-savvy users build their own colony monitoring equipment using open-source software and off-the-shelf hardware components such as Raspberry Pi and Arduino. One of the tools offered is a video-based bee counter. The HiveTool website is run by Paul Vonk, winner of the 2015 Bayer Crop Science Bee Care Community Leadership Award for his work on colony monitoring.
Tom’s original BeeCounter is here: http://www.instructables.com/id/Honey-Bee-Counter
His second, more advanced one is here: http://www.instructables.com/id/Honey-Bee-Counter-II
Raspberry Pi Bee Counter
A bee counter project using the Raspberry Pi computer:
Toward a more-accurate video-based bee counter
It is not that difficult to point a video camera at a hive entrance and stream the view to the internet. In contrast, automating the analysis of that video stream to draw meaning from it is a difficult task.
Research on video-based bee counters itemizes some things that cause difficulty in processing the video stream: the changes in natural light as the day progresses, the speed of flying bees, the tendency of bees to cluster at the entrance and to walk atop one another, the similarity of bees to each other and to their shadows, and so on.
It seems plausible that a video-based bee-counter could be created by providing a view of the hive entrance that mitigates the difficulties that video analysis encounters. For example, the design might make the bees walk through a transparent ‘tunnel’ a few inches long and the width of the hive entrance. The tunnel could be illuminated with natural light filtering through a translucent cone or box above it to minimize variation in illumination. The ceiling of the tunnel could be low enough that only one bee could be in one spot at a time (i.e., not one on the floor and one above it on the tunnel’s ceiling) so that bee images do not overlap, and the bees’ shadows are under the bees where they will not confuse the bee counter. The tunnel would make the bees walk, not fly, so a slower frame rate could be used.
The resolution of the image should be sufficient to distinguish which end of the bee is which, distinguish between workers and drones, and to identify pollen bearers. Such a system would get bonus points for detecting drones and queens. Ideally the analysis software would also detect SHB adults and larvae, wax moths, etc., and it would be fantastic if it could detect Varroa mites riding on bees.
Research on Entrance Activity Monitoring
Monitoring hive entrance activity is an active area of research. Here are just two examples:
- Pollen Bearing Honey Bee Detection in Hive Entrance Video Recorded By Remote Embedded System for Pollination Monitoring. http://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/III-7/51/2016/isprs-annals-III-7-51-2016.pdf
- An index for assessing the foraging activities of honeybees with a Doppler sensor. http://ieeexplore.ieee.org/document/7894090/