As part of my recent independent study with Stuart and Northwestern undergrad Lena Parnassa this spring, I took an initial pass at analyzing the data from our 2023 emergence traps. These data are an important contribution to the broader ENRTF project, which is geared at understanding how ground-nesting bees respond to prescribed fire in prairies. This independent study enabled me to learn a great deal about database organization, coding, and collaboration between data scientists. Before we could run any of our analyses, we had to wade through quite a bit of data cleaning to ensure all our joins were functioning properly. This meant that we had to prioritize the bee analysis rather than the bycatch in our traps (millipedes, grasshoppers, and so forth), so stay tuned for more in that department! We were also working with abundance data rather than species data, as identifications of all the bees we caught in 2023 are still forthcoming. This means that some of the data points in our analysis are most likely incidental, but nevertheless, here’s a visual of what we found! 

Figure 1: Mean bee catch rate by site type. Catch rate refers to the proportion of traps which had bees. 

Figure 2: Bee catch rate by site. Catch rate refers to the proportion of traps which had bees. 

Mean bee catch rate by burn history. Only three sites were 3 years post-burn in 2023, other burn treatments had 7-8 sites.

It looks like remnant prairies had more bees than restorations, but there’s a ton of variation across sites of the same land use type. It’ll be interesting to see what other factors may be associated with this variation, if any. Once we get those species ID’s and confer with our taxonomist, we’d like to tweak our protocol slightly going into this summer to maximize our chances of catching the bees at a given site. We’re considering stocking our traps with propylene glycol to better preserve specimens, trimming the vegetation around traps to make sure bees can find the entrance, and deploying later in the day to give foraging bees time to find their way back to their nests. Looking forward to kicking of the 2024 trapping season!

NOTE: Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).