Friday, October 25, 2019

Climate and Migration

Since returning to our Littleton farm earlier this week, I have noticed that our summer residents, responding to the solar cycle, have left for warmer climes; house wrens, broad-tailed hummingbirds, swallows and blue-gray gnatcatchers no longer grace the property and I have not observed any Swainson's hawks soaring overhead.  On the other hand, our winter residents are slow to move in, currently represented by only a dozen dark-eyed juncos and our lone Townsend's solitaire.

Down at South Platte Park this morning, the winter ducks are beginning to appear but the number of gadwalls, American wigeon, northern shovelers, hooded mergansers, buffleheads and American coot remains relatively low for late October.  Flocks of Canada geese should increase dramatically over the next two weeks but, in recent years, their arrival has been delayed.

Our first significant snowfall may force some mountain songbirds down to the Piedmont but the waterfowl will only come south if they need to (i.e. when lakes and wetlands freeze up north).  As our climate warms, their autumn migration will begin later in the year and, eventually, may shut down altogether.