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After flying for thousands of miles, migratory songbirds reach western New York and are faced with the final obstacle of Lake Ontario. Tired and hungry, the migrating birds need safe places to stop before attempting a lake crossing at night. Stopover habitats are at a premium throughout their migratory routes, and development of the lakeshore has denied many passing birds a local respite.
The Nature Conservancy seeks to protect migrating birds by preserving the areas where they stop in large numbers--only no one knows precisely where they are!
Faced with the lack of data, the Central & Western New York Chapter of The Nature Conservancy teamed up with Audubon New York and scientists from RIT, Hobart and William Smith Colleges, Cornell Lab of Ornithology, Canisius College and NYDOT to solve the migratory stopover site mystery.
Scientists built a GIS model to predict the location of stopover sites. Over the next two years, the model will be tested in the field by volunteer observers. Once the model is verified, it will be published, along with a map of important stopover sites, so that government agencies, landowners and land trusts can use the model to conserve stopover habitats throughout the Great Lakes region.
Below are three songbirds that rely on the Ontario lakeshore as a stopover site.
The Bay-Breasted Warbler
The bay-breasted warbler is a large, handsome warbler with a whitish belly, gray back and chestnut brown crown, throat and sides. Ninety percent of the bay-breasted warbler breeding range lies in a narrow band of Canadian boreal forest. Therefore, safe passage over the Great Lakes is critically important for this species.
Though it breeds in dense spruce forests, during migration it will use any type of woods. Forest fragmentation is a leading cause of declining populations across this species' range, particularly in Maine and the Maritime provinces. Populations are also closely tied to spruce budworm infestations. Abundance can significantly increase during budworm outbreaks, then crash for long periods after.
Bay-breasted warblers are often seen gleaning prey from the mid-level of coniferous trees, particularly on lichen-covered limbs with little foliage. Its primary food items are caterpillars, beetles, flies, moths, and budworms. It sometimes flicks or wags its tail slowly in a small, 15-degree arc while feeding.
The bay-breasted’s song is composed of 5-10 very high, thin, squeaking single or double notes, varying little in pitch, rendered as se-atzee-atzee, or seetzy-seetzy, seetzy, seetzy-see. The number and pattern of single and double notes varies among individuals. The song is generally soft and very high-pitched, almost indistinguishable from the Cape May warbler.
The Black-Throated Blue Warbler
A bird of the deep forest, the black-throated blue warbler breeds in the northeastern United States and southeastern Canada. On migration to its Caribbean wintering grounds it can be seen in a variety of habitats, including forest, forest edges, parks, and gardens.
The male is one of the easier warblers to identify because it retains its striking blue plumage year round. It is blue-gray above, white below, with a black face, throat, and sides. The female is a dull olive-green, with narrow white eyebrow and usually a small, square, white wing patch.
Studies show that black-throated blue mortality rates are at least 15 times higher during the migration than during summer and winter. So while populations on its breeding and wintering grounds are relatively stable, the survival wildcard for this species is linked to the quality and quantity of migratory stopover sites as well as unpredictable migratory events such as storms and tower kills.
The black-throated blue warbler forages in lower to mid-levels of the forest, gleaning insects from the underside of leaves. It feeds on fruits, seeds, nectar and tree sap in the winter. In summer, their diet transitions to insects such as moths, tent caterpillars, aphids, beetles and flies.
The warbler’s buzzy zoo zoo zoo zee song can often be heard drifting from the well-developed understory where it nests.
The Wood Thrush
Even though it is a common species of Eastern forests, the wood thrush is of high conservation concern because of steady, long-term population declines throughout most of its range. At a rate of -1.7 percent per year, it’s experiencing one of the fastest rates of decline of any songbird. A number of causes have been suggested, including habitat loss in its winter range and forest fragmentation in its breeding range.
The wood thrush migrates primarily at night and travels an average distance of 2,200 kilometers between its breeding (southeastern Canada throughout the eastern U.S) and wintering grounds (lowlands of Central America, from southern Mexico to western Panama).
Thrushes forage by gleaning and probing in the leaf litter on the forest floor. They are fond of protein-rich insects while raising their young, but their diet transitions to energy-rich fruits, especially berries, in fall and winter.
The male wood thrush is larger than other forest thrushes but slightly smaller than American robin. Its crown and nape are reddish-brown, which changes to olive-brown on back, wings, and tail. It has a white eye-ring and white underparts with large dark spots on throat, breast, sides, and flanks. Females are similar.
The wood thrush sings a series of yodeled ee-oh-lay phrases that end on a complex, flute-like note. Because the male can sing two notes at once, his song is actually a one-bird duet.
Nature picture credits (top to bottom, left to right): Photo © August Allen/Creative Commons (bird migration); Photo © Jerry Oldenettel/Creative Commons (hooded warbler); Photo © Stuart Oikawa/Creative Commons (bay-breasted warbler); Photo © Jerry Oldenettel/Creative Commons (black-throated blue warbler); Photo Joby Joseph/Creative Commons (wood thrush).
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