I saw my first “V” formation of Canada geese of this fall and it got me thinking about migratory triggers. Here in North America the days are starting to get notably shorter, sunset is now about an hour earlier than it was in June. Most animals have circadian rhythms that are tuned to environmental cues like day length. In many species, the shorter day length along with cooler temperatures is the sign of coming winter and triggers migratory behavior. InsideRead more