What’s all the thrashing about?

COURTESY KENNETH COLE SCHNEIDER
The hillside behind our cabin is a meadow bounded on two sides by woodland, mostly deciduous on the north and mostly coniferous on the west. The eastern boundary is a stream, beyond which is the grove of mature trees in which our cabin sits and the scraggly lawns and ericads that live beneath them. To the south there are several acres of field. I distinguish between meadows and fields by how often they are cut; fields are cut several times a year and so are dominated by grasses.

This is a lot of edge and of several varieties. The boundaries between plant communities are generally the most diverse places for flora and fauna. Consequently, on my morning walks with the dog, I see a mix of species. This morning I was surprised by a male cardinal, cheeping at the edge of the deciduous woodland. This is a backyard species at this latitude and altitude; I wouldn’t expect to see him deeper into the woods. Chickadees and titmice are woodland species that come to the edge of that habitat to forage. The golden-crowned kinglets that I heard today are woodland species that are migrating through and I don’t expect to see them later in the year. The phoebes and chipping sparrows that were fussing about near the barn are classic edge species, always hovering between an open space and a woodlot.

This is the kind of place I would hope to see a brown thrasher (Toxostoma rufum), and yet I have not, as yet. From what I gather from Arthur Cleveland Bent’s Life Histories of North American Nuthatches, Wrens, Thrashers, and Their Allies, we do not have enough overgrown shrubs to suit them. The landowner mows the meadow once a year and he seems to have carved it out of a woodlot relatively recently. Consequently, there are no mature shrubs either in the meadow or at the edges of the woods.

Bent is fond of the brown thrasher, giving it 13 pages of text and six photographs. He notes that its preferred habitat varies much over its wide range. Bent lived in eastern Massachusetts, where he described seeing the catbird, another mimic thrush, nesting in his own backyard “a stone’s throw from brick and mortar,” but he never saw a brown thrasher there. In New England, he writes, they are birds “of the rural, woodland, and farming districts, living in bushy pastures, sproutlands, brier patches, tangles along fences, dry thickets, brushy hillsides, and the edges of woodlands, almost always far from human habitation.”

This conforms exactly with my own experience in central New York. They were downright abundant in the Finger Lakes National Forest, which in spite of its name is a mixture of grazing land and woodlots on the broad ridge between Cayuga and Seneca lakes. The federal government seized several farms in the 1930s (for reasons never adequately explained) and have maintained them in state much as they were, but sans human habitation. The pastures are leased by farmers and are full of cattle three seasons of each year, but the edges and fence lines are not tended as they would be by an actual landowner and so are thick with all kinds of shrubs.

I remember walking down one overgrown edge that separated a deciduous woodlot from a grazed field dotted with large multiflora bushes. I seemed to see brown thrashers every 40 or 50 yards, apparently one nesting pair after another. These birds foraged on the ground along the path that paralleled the almost hidden barbed wire fence and sang from perches at the edge of the forest, usually about 10 feet from the ground.

They are a large species, longer than a robin—the greater length mostly in its dramatic tail—but with shorter, more rounded wings, and a slightly down-curved bill. Their heads, backs and tails are a rich red-brown—they were called fox-coloured thrushes in the 18th century— and their white undersides are strongly streaked with black from their throats to under their tails. The two wing bars are bi-colored, each one parallel lines of black and white. Finally, their irises are bright golden-yellow with black pupils.

As mimic thrushes (Mimidae), they are related to the catbird and the mockingbird. All three create songs that are strings of quite varied pitch and tone, usually single-syllables but sometimes double. The catbird does not repeat a given note and its song sounds relatively disjointed. The thrasher repeats each note in pairs, giving it a clockwork quality. The mockingbird repeats the same note five or six times. All of them mimic other species (and non-bird sounds), but because of the repetition, it is easier to pick these out from mockingbirds’ songs.

The mockingbird is definitely more aggressive than its cousins; it will attack nearly everything that comes near its nest and its general behavior is the opposite of skulking. The catbird is at the other end of this spectrum and the thrasher seems to be in the middle. I was surprised to read in Bent that in the Midwest, where brown thrashers do deign to nest near human habitation, they and catbirds are mortal enemies and may fight to the death over a choice nest site. This seems so out of character for the gentle, shy catbird that I know.

The thrashers are one of those groups with a single widespread generalist species in the east and multiple specialist species in the western U.S. Other examples include buntings, towhees, jays, kingbirds, and (before they were consolidated into one species) juncos. This has been ascribed to the relatively homogeneous habitat of the eastern half of the U.S., uninterrupted by dramatic shifts in rainfall and vegetation caused by large mountain ranges. In the case of the thrashers though, we got the flashy one.

Bill Chaisson has been a birdwatcher for over 50 years. He is a former managing editor of the Eagle Times. He now lives and works in Wilmot. Contact him at [email protected].