Possibly its development not necessarily modest temperature changes that causes species to relocate?
“Working out of Washington University in St. Louis (WUSTL), biologists Tiffany Knight and Laura Burkle discovered that 50 percent of the local bee species in central Illinois had vanished, some pollinators were active before their associated plants had bloomed, some plants weren’t visited as frequently, and the bees that did visit weren’t carrying as much usable pollen.”