Airdate: May 08, 2001
Scientist: David Inouye
Early Spring: Unexpected Conditions
Warming weather and increased snowfall send mixed signals to migrating species.
Early Spring - Unexpected Conditions
Music; Ambience: Dawn chorus
JM: There is strong evidence that in recent years the first signs of spring have been coming earlier. Stimulated by warming temperatures, plants are blooming sooner and migrating animals are showing up earlier in the year than they usually do. But at higher altitudes, these harbingers of spring have had to face unexpected conditions. I'm Jim Metzner, and this is the Pulse of the Planet. Global warming is being blamed for a variety of weather phenomena - including an increase in snowfall.
DI: "There is more precipitation during the winter at higher altitudes because, for instance, the increased warmth of the air is causing increased evaporation, which means that there's more water vapor in the air, and that's falling down as snowfall during the winter."
JM: David Inouye is director of the graduate program of conservation biology at the University of Maryland. He says that warming weather and increased snowfall send mixed signals to migrating species.
DI: "The field station where I do my research, a place called the Rocky Mountain Biological Laboratory, is up at nine thousand five hundred feet, in the West Elk mountains in Colorado and some of the birds that are arriving there after having over-wintered at lower latitudes and altitudes, are arriving earlier and earlier each year, because they are getting cues at lower altitudes that spring is coming earlier and earlier. But at the higher altitude, where snow seems to be controlling the growing season, the winter has been lasting longer and longer because there is more snow falling and therefore, when these birds like robins arrive, they are somewhat confused to find that it is still winter at these summer breeding grounds, when the cues that they'd gotten at lower altitudes were that spring is coming earlier and earlier and it's time to go breed in the mountains."
JM: We'll hear more about the signs of spring arriving early in future programs. Pulse of the Planet is presented by the National Science Foundation I'm Jim Metzner.