Video assessment of forager losses in honeybees
The assessment of forager losses is currently often conducted using a rather small number of bees (often about 100 or less, see Henry, 2012), which receive radio tags for identification. Honeybees are then registered when they return to the hive. Since this method is time and cost intensive and since due to the small number of bees assessed it involves a considerable uncertainty (e.g. in Henry et al., 2012, the coefficient of variation (CV) of homing success is up to 38%) we developed alternative methods based on video analysis, which require minimum effort and which result in much more accurate and less variable results.
Automatic assessment of forager losses using VideoCounter
Our software VideoCounter is used in conjungtion with a camera mounted above the entrance of the hive to automatically detect and count individuals bees. Individual honeybees are detected using pattern-recognition algorithms and the movement speed and direction is tracked. A virtual gate, i.e. a user defined virtual red line drawn in the software screen, is used to count individuals leaving and entering the hive. This method allows counting honeybees without obstructing the hive entry, which other methods usually do. After entering the start and end date and time for automated monitoring, entering and leaving honeybees are automatically tracked over one or several days. No supervision is required. After tracking over several days, results are available in both graphical and tabular form. The intra-day activity of foragers for one day is exemplarily shown in the figure below. Honeybees started to forage around sunrise and forager activity lasted until shortly after sunset.