Waiting for the snow to melt…
In recent decades, rapid warming has altered the environmental conditions experienced by many organisms. One of the most commonly documented biological responses to warming is range shifts, in which populations shift their distributions primarily towards higher latitudes and altitudes to track areas of climatically suitable habitat. Range shifts in bees may be of particular interest. Many aspects of bee life-histories, including their development, survival, and reproduction, are directly linked to temperature; yet bees are also indirectly affected by the availability of other factors such as floral resource abundance and nest-site availability, which may themselves be affected by temperature. I am proposing two field studies that investigate the potential for upslope range shifts in cavity-nesting bees by exploring the variables that determine their upper range limits. In the first study, I ask whether the potential for range shifts in cavity-nesting bees is limited by the lack of nesting cavities at high elevations where trees and dead wood (nesting substrates) may be scarce. In the second study, I ask whether the potential for range shifts in cavity-nesting bees is limited by the short duration of periods of favorable temperatures for offspring development at high-elevations. My proposed fieldwork will combine both observational and experimental techniques to address these questions.