This is the time of the year when each morning seems to bring a new bird into earshot when I walk the dog or simply go out for a stroll. This morning it was the chestnut-sided warbler, with his loud “please ta meet meet meetcha” song. He has others, which will be rolled out in due time. Yesterday the new arrival was the black-throated blue warbler, which also has more than one song. The one I heard yesterday and this morning has three or four pure notes at different pitches and ending with a wheezy trill that descends in pitch.
These are both edge dwellers, hovering at the boundary between the forest and the meadow. Their territories do not seem to overlap. On my property the black-throated blue prefers a patch of birch saplings backed by mostly coniferous forest, while the chestnut-sided tends to forage and live alongside and in the deciduous forest on the northern border of the meadow.
Another recent returnee is singing from across the road in the wet woods to the east of us. Occasionally he ventures over into the mature hardwoods that tower over our cabin, which is when I appreciate the penetrating nature of his seemingly quiet song. Although he seems to prefer the swamp, it isn’t a veery, but a wood thrush (Hylocichla mustelina). His ee-o-lay phrase is the one that I recognize and use to separate him from his cousin the hermit thrush. They are both beautiful singers, but I think of the hermit as more Romantic and dramatic in its delivery, while the wood thrush is more Baroque and orderly.
When we first moved into our house on Spy Hill in Beacon, N.Y. in the early 1970s, the elderly judge and his wife who lived there before us had “let the property go” as they had less energy to maintain it. There was a grove of perhaps 15-year old Norway maple saplings in the southwest corner of the parcel where a wood thrush lived and sang. It was an oddly sterile little copse with hardly any undergrowth because the monoculture of exotic maples drank all the
water and heavily shaded the ground beneath them. But it was good enough for a wood thrush. The second year we lived there, my parents chose to cut down the maples in order to get a view of the river and take shade off the vegetable garden. The thrush, of course, did not return.
My current neighborhood thrush lives in a 10- to 15-acre tangle of red maple and alder, which is more customary. According to Arthur Cleveland Bent, “These birds are found in low, cool, damp forests, often near streams. This probably follows because of the need of mud and damp plant material, which are used in the construction of the nest.” Bent cites Arthur A. Allen’s belief that this species avoids bright sunshine, “probably because its eyes are so large that too much sunlight makes the bird uncomfortable, so that it keeps to thick woods or ravines where there is plenty of vegetation and resulting shade.”
Bent seems quite fond of this species and devotes many pages of Life Histories of North American Thrushes, Kinglets, and Their Allies (1949) to it. He documents the northward spread of the species, paying particular attention to New Hampshire (he lived in eastern Massachusetts). Much of this expansion took place between 1890 and 1910. He cites M.W. Provost (1939): “Before the advent of the white man, the Wood Thrush was not found farther north than the Lakes Region in central New Hampshire and Hanover in the Connecticut Valley. In the two decades 1890-1910 there was a remarkable invasion of the White Mountain valleys by this bird. Today it is by no means rare in the transition valleys up to 2,000 feet.”
In The Birds of New Hampshire (2013) Keith and Fox write: “It was first reported in the state in 1894, expanded in the state until about 1982 and has declined ever since.” They surmise from the existing historical data that the wood thrush moved north into southern New England in the 1700s. During the reforestation of the region in the early 20th century, it expanded rapidly.
Kimball C. Elkins, writing in the Atlas of Breeding Birds in New Hampshire (1994), notes that it “the largest of the spotted-breasted thrushes” and is recognized by its reddish-brown head (the hermit thrush as a reddish-brown tail). He describes them as dominant over the smaller hermit
thrush and veery, displacing both where their territories overlap. The competition between hermit and wood thrushes is more intense because both are ground foragers.
Older sources describe the wood thrushes diet as mostly insects during the breeding season, but recent writers note its preference for snails and slugs, both of which are rich in calcium and allow the birds to lay eggs with strong shells. In New York, acid rain in the Adirondacks has depleted soils of calcium and decreased the gastropod populations. “As the snail goes, so goes the thrush,” wrote Eden McLane in the fall 2004 issue of The Land Steward. These birds do not metabolize calcium very efficiently; they need 10-15 times as much in their diet as a similarly-sized mammal.
Part of the North American population spends the colder months in Central America, where deforestation has decimated their wintering grounds. In much of their breeding range, suburbanization has cut up the forest into little pieces. Wood thrushes prefer larger tracts of woodland. Consequently their numbers have been declining for decades. Their numbers are half of what they were in 1966. They have been put on the Yellow Watch List for birds most at risk of extinction without significant conservation actions to reverse declines and reduce threats.
Bill Chaisson has been a birdwatcher for over 50 years. He is a former manager of the Eagle Times. He now lives and works in Wilmot. Contact him at email@example.com.