Bombus vosnesenskii mark-recapture pilot survey: Mt. Ashland 2025

The objective of this survey was to estimate the local population size of Bombus vosnesenskii, a common bumblebee species in the Mt. Ashland region, as a pilot effort to inform future mark–recapture studies in the area. 

Bees were captured within a ~140-meter survey radius centered on a designated marking station using insect nets. Upon capture, individuals were transferred to glass holding vials, which were then placed on ice in small coolers for 5-10 minutes. This cooling period allowed bees to become sufficiently calm for safe handling and precise marking.

Once bees exhibited reduced activity, they were carefully transferred into queen bee marking tubes (product link), positioning the thorax outward. A small dot of red, water-based, non-toxic acrylic paint was then applied to the thorax using a fine-tip paint pen.

After marking, all bees were released at the central marking station rather than at their original capture locations. A total of 300 B. vosnesenskii individuals were marked on July 7th, between approximately 9:00 AM and 3:00 PM. Most of the marked bees were workers; however, five queens were also marked and released.

On July 8th,  we returned to the site and conducted visual surveys alongside volunteers within the same ~140-meter radius. Both marked and unmarked bees were recorded, and these counts were subsequently used to generate a population estimate for B. vosnesenskii at the site.