Williams, P., S.R. Colla & Z. Xie. 2009. Bumblebee vulnerability: common correlates of winners and losers across three continents. Conservation Biology 23: 931-940.
Abstract: It is widely agreed that in many parts of the world some bumblebee species have declined and that this has often been driven by reductions in the abundance of food plants. There is much less agreement about how changes in food plants affect the vulnerability of some bumblebee species more than others. We aim to identify the general characteristics correlated with degrees of decline between relative winners and losers by comparing three independent faunas, in Britain, Ontario, and Sichuan. For this preliminary study of available survey data, we attempt to assess: competition with congeners; size of climatic range; proximity to climatic range edge; food specialization; timing of activity; body size; and size of geographical range. A meta-analysis of these correlations showed the strongest support for the predictions of hypotheses that decline susceptibility is greatest for species (1) with narrow climatic ranges and (2) where species occur closest to the edges of those climatic ranges. There was also borderline non-significant support for the hypothesis that decline susceptibility is greatest for species (3) with queens that become active later in the season. We make recommendations for conservation action plans.