Canaries in the coalmine
As I passed the kitchen windows last Friday (4/10), a brilliant red streak caught my eye. I followed the streak to a branch in one of the large poplars at the corner of the deck. There in all his freshly plumaged glory sat a scarlet tanager. The scarlet so bright and vivid it was screaming next to the jet-black wings.
Now don’t tell anyone associated with Cornell’s Back Yard Bird Count or I’ll have to recant because it’s entirely too early for a scarlet tanager in the mountains of Western North Carolina. It would have to be an aberrant cardinal or a cardinal in poor light.
One of my many shortcomings as a birder is the fact that I don’t take notes or record observations. But I have friends that do. So I called a birder friend that does (Bob Olthoff) and asked how last Friday compared to his earliest scarlet tanager record. Bob said the bird in my yard was a good 10 days earlier than his earliest record.
This spring also happens to be my earliest arrival date for blue-headed vireo. I had one singing in my yard on March 23 this year. I don’t know how early that was but it was early. I didn’t think much of it because blue-headed vireos are early migrants. But add the tanager and it makes you go hmmmm.
I have casually perused some of the information regarding global warming and migration over the last few years. The early appearance of the scarlet tanager caused me to turn to some of that data again.
The appearance of one or two early migrants means little, in itself. But, thankfully, many birders are better at keeping records than I and studies are beginning to show bird-population trends consistent with warming trends. Models predicted that birds would shift their home range northward and/or toward higher elevations as temperatures rise.
Research of data collected for the past 24 years shows that warblers like prothonotary, blue-winged, golden-winged, Cape May and others have expanded their range northward by an average of 65 miles during this timeframe. And one study of 20 species of migratory birds showed early spring arrival dates in 1994 to be 21 days earlier than in 1965.
The implications regarding effects of global warming on bird population distributions and behavior are myriad and complex. A quick primer can be found at www.abcbirds.org/conservationissues/globalwarming/global_warming_factsheet.pdf, at the American Bird Conservancy’s website. Or for my unplugged friends who find the listing of URLs a bit biased, you can call Darin Schroeder at American Bird Conservancy, 202.234.7181.
The canary in the coalmine comparison is troubling. The only way the miners knew they must leave and remedy the conditions in the mine was if the canary was dead. If we wait for mass extinction of our multi-colored, nightingale-voiced canaries before we begin to address the issues of climate change we will indeed wake up to Rachel Carson’s silent spring.