And the hits just keep on coming. A varied thrush visited a feeder in Milford for several days at the end of January.
Add this one to the growing list of birds that shouldn’t be in Maine this winter, but are.
The varied thrush is similar in size, shape and behavior to an American robin. Its range is confined to the Pacific Northwest, except when it isn’t.
I’ve enjoyed multiple encounters in Oregon, Washington and Alaska on the west side of the Rockies. I’ve had the pleasure of their company in Montana and Alberta on the eastern slope.
I’ve also seen two in Maine. A dozen years ago, I was summoned to a house in Old Town to confirm a varied thrush visiting a feeder.
Varied thrushes have a reputation for wandering. They can get away with it because, like all thrushes, they have a flexible diet. They rely on insects hiding in leaf litter during breeding season, but subsist on nuts and berries in winter. They’re not shy about visiting feeders when hungry.
Not to be outdone, I’m aware of at least two Townsend’s solitaires that have wandered into Maine. In breeding season, they stay west of the Mississippi River, generally in scrubby alpine forests. They, too, can roam a bit in winter.
I wish I could hear either of these two birds sing in Maine. The song of the varied thrush is unusual and haunting, reminiscent of a train whistle blowing from the top of a tall conifer.
The Townsend’s solitaire is such a vocalist that it can compete with northern mockingbirds. The birds can burst into extended song any time of year. I watched them sing in Oregon last October, and they simply floored me.
Other western birds are visiting Maine this winter. A hepatic tanager, normally found near the Mexican border, is still in Stockton Springs.
A spotted towhee, which nests on the far side of the Mississippi, is loitering in Kittery. Ditto for at least two western tanagers. A lark sparrow is in Corinna. Lark sparrows nest as near as Ohio, but wander regularly.
A black vulture made headlines after being rescued in Bar Harbor. The bird was taken to the Acadia Wildlife Center.
All these birds are unusual, but some are more unusual than others. Birds that venture outside of their normal ranges are called vagrants or accidentals. They roughly fall into two categories.
In the first category, some birds are simply prone to wandering. The varied thrush, Townsend’s solitaire, western tanager and lark sparrow show up in Maine periodically, despite the distance.
The black vulture didn’t travel far. Its range extends from the deep south all the way into southern New England. They don’t migrate much, and many can be found overwintering in Connecticut.
Though still rare, black vultures are drifting into southern Maine more often. Another was reported in Portland last week. I suspect they will become Maine residents within the next decade or two.
Yeah, climate change.
In the second category are birds that shouldn’t be here ever. The hepatic tanager, native to the Southwest, fits this category. So did the infamous gre at black hawk in 2018. The more infamous Stellar’s sea eagle is even more impossible.
Some birds are blown off course. Weather-related misdirection primarily affects species in migration.
Some birds have a navigational screw loose. Genetic defects can throw off a bird’s compass, causing it to veer off course, sometimes dramatically.
Some species are pioneers. Individual birds sometimes roam outside their normal ranges, perhaps as an evolutionary strategy for colonizing new places when their traditional places become degraded.
Unfortunately, that exploring instinct usually doesn’t end well for the pioneers. But enough birds may survive to benefit the species.
The pioneering strategy is most apparent in birds that engage in post-breeding dispersal. Before their fall migration, some species will first wander in all directions at the end of nesting season.
The best local example is provided by great egrets. They nest in southern Maine, but once the kids are off the nest, they spread northward in late summer prior to heading south for the winter.
Although most vagrant activity can be explained by science, we’ve had many more wanderers than usual this winter.
Are these birds responding to climate change, or just abnormal weather? Alternatively, are Mainers simply getting better at identifying weird birds when they show up?
The popularity of birding and bird-feeding continues to increase. Maybe we’re all just becoming more skilled.