Movement of nest‐searching bumblebee queens reflects nesting habitat quality

Abstract

Movement of foraging animals can be used as an indirect index of habitat quality because movement patterns are expected to shift in association with resources resulting in increased time spent in high-quality habitat. Here, we observed movement of bumblebee (Bombus impatiens) queens as an indirect metric of nesting habitat quality. At a farm in Massachusetts, we recorded flight paths by visual observation of nest-searching B. impatiens queens in three land cover types (hay fields, meadows and forests). According to previous research at this field site, these land cover types represent both high-quality (meadows, forests) and low-quality habitat (hay fields) for nesting bumblebees. Using flight path data, we estimated diffusion coefficients of nest-searching queens (i.e., the rate at which queens explore habitat during nest-searching), as an integrative measure of movement. We found that nest-searching queens explored meadows and forests more slowly than hay fields; we calculated diffusion coefficients of 0.198, 0.272, and 0.762 m2 s−1 for bees searching for nests in meadows, forests, and hay fields, respectively. In hay fields, nest-searching queens had smaller step lengths and straighter flightpaths than in other land cover types. Nesting ecology of bumblebees is a key knowledge gap. We showed that nest-searching queens search more thoroughly in areas associated with previously reported high nest densities. Therefore, our research suggests that behaviour of nest-searching queens can also be a proxy for nesting habitat quality. Extending these methods to other Bombus species in other landscapes would be a valuable direction for future research.