October 07, 2014
On my morning walk the other day, I happened on a small bird in obvious distress lying on the sidewalk. Apparently, it had flown into a building and injured itself – or that's what staff at the Schuylkill Center for Environmental Education said when I called them to see what I could do to help the poor thing. Rick Schubert, director of wildlife rehabilitation at the center, said the bird was probably migrating south, since it didn't sound, from my description, like a bird that was native to the area. Schubert went on to say that migrating species of birds established their migratory routes long before cities were a feature of the landscape and that they are not particularly good at navigating around tall buildings.
Soon enough, the bird died, and I was overcome by grief – not just for the little voyager that never made it to its destination, but for the precarious state of all our birds. As I learned from the Audubon Society's Audubon Birds and Climate Report, which was issued last month, half of all North American birds are severely threatened by climate change.
One of the most dramatic illustrations of the phenomenon can be seen near my home in Philadelphia. The rufa red knot, a bird smaller than a robin, migrates more than nine thousand miles every spring from the tip of Patagonia to the Canadian arctic, and makes the return journey every fall. The birds time their three-month trip north to arrive at the southern Jersey shore for the horseshoe crab spawning season; the abundance of food enables them to double their weight in preparation for the remainder of the journey north. Sadly, horseshoe crabs were overfished for bait in the 1990s, and that has resulted in a 70 percent drop in the rufa red knot population. Better crab harvest management since then has stabilized the declining bird population, but according to the U.S. Fish & Wildlife Service, the red knot is "particularly vulnerable to climate change."