http://stream.publicbroadcasting.net/production/mp3/wamc/local-wamc-955646.mp3
Albany, NY – In today's Academic Minute, Dr. Douglas Robinson of Mount Saint Mary College in Newburgh, NY, explains the environmental factors that trigger migration instincts in birds.
Douglas Robinson is an assistant professor at Mount Saint Mary College in Newburgh, NY, where he teaches classes on animal behavior, ecology, ornithology, vertebrate biology, general biology, environmental science, and anatomy and physiology. He holds a Ph.D. from Binghamton University and his research efforts focus on how behavior is shaped by ecological and social environments. One of his ongoing research projects seeks to understand the impact of antibiotic resistant bacteria on behavior and survival in American Crows in the mid-Hudson Valley.
Dr. Douglas Robinson - Bird Migration
In the course of a single year, nearly the Earth's birds will migrate some distance at some time. During the spring in northern temperate regions, most of the birds that actually breed "here" will return from points South as the ice and snow melt in the warming sun of the spring. Some species, such as the American Robin, only flew to the southern Atlantic states; other species, including the Sandhill Crane, wintered along the coast of the Gulf of Mexico, while still others, including our brightest and best singers, the warblers, flew to the tropics and the southern hemisphere.
For species wintering along the equator, internal annual clocks promote increased restlessness and the signal to return to the northern breeding grounds. For other species, the urge to return is cued by increasing day length. Even longer day lengths after they arrive will stimulate production of hormones that trigger the growth of reproductive organs. But migrants may stop south of their final destination and then for the final push, use temperature, rainfall, atmospheric conditions, and food abundance to "fine tune" their arrival to their summer homes.
It is sensitivity to warming conditions, and perhaps earlier food abundance, that seem to be resulting in earlier and earlier spring arrivals of some species as global temperatures increase. The ability to time the arrival on breeding grounds has been strongly selected, as those who made mistakes or relied on the "wrong" cue paid with fewer offspring or even their own deaths. Look for those success stories of species to arrive in your yard in the near future!