Counting bees like birds: Roadside surveys for bumble bees

The status of bumble bees is of global concern, and in Canada seven species have been assessed at some level of conservation risk. Like many declining birds, these bumble bees have wide ranges, but unlike birds, there are no practical, widespread bee monitoring programs in place that can detect range-wide trends. In an attempt to fill this gap, we began a series of roadside surveys in the Yukon based on the design of the continental Breeding Bird Survey (BBS). Similar programs have been tested previously in the eastern U.S.

From 2017-2021, we conducted 10-18 surveys per year, covering 30 survey routes in total. Each survey included 10 stops, and bees were netted for 10 minutes at each stop; all specimens were vouchered, identified and databased. Over the five years of surveys, 21 of the region's 28 bumble bee species were recorded, including all three of the possible species at risk (Bombus mckayi, B. bohemicus, and B. suckleyi). Bombus mckayi was the third most abundant sampled species; 22 specimens of B. bohemicus and 10 specimens of B. suckleyi were also collected. We estimated bumble bee trends using similar models to those used for the BBS.

This method has practical advantages over trapping and photographic monitoring, especially where human resources are limited. Time per specimen in the field is minimized and only one visit to each site is needed annually. Weather effects are minimized, and samples are not lost through disturbance of traps by wildlife.