Bumble bee question

I guess I take bumblebees for granted. They're always around, happily pollinating a myriad of plants and doing the job once done primarily by honeybees, . which have declined due to a mysterious condition called Colony Collapse Disorder, along with other potent stressors. But these furry and typically gentle insects may be experiencing their own troubles, and that's cause for concern, given all the vital work they do. In a new paper in Science, biologists, using old and new records, tracked an array of range contractions that many species have experienced in the last 100 or so years, and the culprit seems to be climate change. The bees, clad in eternal fur coats, don't like particularly warm weather, and when this occurs as temperatures rise, the bumblebees in the affected area tend to drop out of the picture. Ominously, this has not, so far, been accompanied by an expansion north in range. This may just be slow to take place—bumblebees do not reproduce in droves, so rapid population increases don't often occur—or there might be other barriers. Our bumblebees, thankfully, appear to be holding their own, but clearly, they bear watching. Perhaps I should start the observation process by finally learning the names of our cast of characters.