Behavioral observations
To estimate the activity level of bees as a possible predictor of water loss, we performed behavioral scan samples of each individual every 20 minutes throughout the 3-hour assay. We recorded behaviors according to a standard ethogram and observed three unique behaviors during the assays: 1) idle, 2) walking/climbing, and 3) self-grooming. No social behaviors, including agonistic interactions, were observed. We estimated the proportion of active time as the number of scan samples where an active behavior (walking/climbing) was recorded divided by the total number of scan samples. Following assays, bees were rehydrated and returned to their nest site, excluding those sacrificed to estimate dry mass.