Fig. 2.

Assessment of colony strength. Colony strength was assessed by visual count of active colonized frames within each hive. Colony strength was assessed prior to departure, after arrival, and at semi-regular intervals. Colonies that lost thermoregulation during shipping are indicated by an asterisk (*). Colonies with fewer active frames experience disproportionate loss during shipping, while larger colonies maintain stable populations (Z = −2.191, P < 0.05). Departure strength, arrival strength, and the loss of thermoregulation during shipping all significantly interact to affect colony survival, with smaller colonies failing faster than larger colonies (Z = −4.366, P < 0.0001).