Yesterday morning I thought I might make this week’s piece about birding in snow, then, in true Cape Cod fashion, that lovely snow was gone within a few hours. So now I’m back to enumerating the various western vagrant birds that continue to infiltrate the area. Some of the checklists birders are submitting from the Cape right now look like they came from western Colorado in July. So what is going on? Surely this is somehow related to climate change or western forest fires, right? Or maybe us modern birders are just better at finding them with our smartphone apps, top notch optics, and much better field guides, plus various recordings to call birds in? On all accounts the answer is “not really,” but we’ll get to that later.
Most recently, a Western Grebe showed up on Mashpee Pond, likely the same bird that spent last winter between there and nearby John’s Pond. If you’ve ever seen the more common Horned Grebe paddling around just off a winter beach, imagine it was stretched out on a medieval rack and you’ve got the much lankier Western Grebe. These birds of western lakes are known for some fantastic breeding displays, wherein the members of the pair engage in synchronized swimming even the Russian judges would award a 10, as well as full on, side-by-side foot races atop the water, Jesus style.
Western Tanagers, gorgeous yellow, red, and black birds of western mountains, have been turning up in a seeming biblical plague the last few years – two are being seen together along the canal at Scusset Beach, with several other sightings from Boston to Nantucket this winter.
In Maine, a sometimes Cape Cod birder named Tom Aversa made the jaw-dropping discovery of a Hepatic Tanager while scouting for a Mid-Coast area Christmas Bird Count. This species of Central and South America, whose name reflects the male’s livery-red color, barely gets into the mountains of Arizona and New Mexico, and had never been recorded on the East Coast.
Other western birds around include the Western Kingbird and Lark Sparrow continuing in Eastham, Western Willets in Chatham and Nantucket, and a Dickcissel at a feeder in Wellfleet. These species are more expected, falling somewhere between an expected annual vagrant, like the Western Kingbird, and a regular migrant like the Western Willet. Dickcissels, midwestern grassland birds who normally winter in Venezuela, are oddly regular here in fall migration but rarely stay the winter.
To get at the question of why all these western birds are showing up, I got out my trusty copy of The Birds of Massachusetts authored by Dick Veit and my Mass Audubon colleague Wayne Petersen. While it remains frozen in the time before 1993, it provides the historical context necessary to process the patterns we see today. While the eBird database we birders all depend on now shows just 12 records of Western Grebe for Massachusetts, they used to be more commonly seen - back in 1934 a single flock of 12 wintered in Gloucester. Ditto the Western Tanager – while we are all thinking this is some new phenomenon, in fact we see fewer Western Tanagers in winter than we did in the 1950s and 60s. The same holds true for Lark Sparrows and Dickcissels. And that’s despite many fewer birders and almost none with cameras back then.
So, instead of asking if all these western birds are here because of climate change, fires, or more and better equipped birders, the better question may be “why we do see fewer of these western species than we did in the early and middle part of the 20th centuries?” The simple answer may be that, thanks to habitat loss on both the breeding and wintering grounds, there are just fewer of them. All the German optics, smartphone apps, and high-powered digital cameras in the world can’t conjure up birds that aren’t there.
