
North American Birds Are Shrinking, Likely a Result of the Warming Climate
A new study found significant declines in bird body sizes after analyzing decades of data collected by Chicago’s Field Museum.
Female or immature. Photo: Andy Reago and Chrissy McClarren/Flickr (CC-BY-2.0)
Leiothlypis peregrina
Conservation status | Local breeding populations rise and fall, apparently in response to outbreaks of certain forest insects, such as spruce budworm. Overall numbers of this warbler seem healthy. |
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Family | Wood Warblers |
Habitat | Deciduous and mixed forests; in migration, groves, brush. Breeds in bogs, swamps, and forests. Prefers openings in second growth balsam-tamarack bogs, or aspen and pine woods, or edges of dense spruce forest. Nests near slight depressions of boggy ground. During spring migration, mostly high in trees. During fall migration, often lower in saplings, brush, weedy fields. |
Forages in the outer foliage of trees, sometimes hanging head downward. Takes insects in dense patches of weeds. In summer, male may feed mostly in treetops, female remaining nearer the ground. Forages in flocks of up to 200 on wintering grounds, often in coffee plantations.
5-6, sometimes 4-7. May lay more eggs during outbreaks of spruce budworm. Eggs white, with some marks of brown or purple. Rarely parasitized by cowbirds. Incubation by female only, 11-12 days. Young: Development and care of the young, and age when they leave the nest, are not well known. Probably 1 brood per year.
Development and care of the young, and age when they leave the nest, are not well known. Probably 1 brood per year.
Mostly insects, some berries and nectar. In summer feeds mainly on insects, including caterpillars, scale insects, aphids, beetles, flies, ants, leafhoppers, and others; also spiders. Takes nectar from catkins, and some juice from grapes. In winter in the tropics, feeds on nectar, berries, and the protein-rich structures that cecropia trees produce at base of leaves.
Male has loud repetitious song on breeding territory. In ideal habitat, nests are closely spaced in loose colonies. During courtship, male performs song flight up to 60' above the ground. Nest: Concealed in a depression on ground under bushes or overhanging grass. Site is usually on mossy hummock in a wet area, but will nest on fairly dry ground on steep hillsides. Nest (built by female) is open cup made of thin grass stems; lined with fine dry grass, porcupine quills, or moose hair.
Audubon’s scientists have used 140 million bird observations and sophisticated climate models to project how climate change will affect this bird’s range in the future.
Zoom in to see how this species’s current range will shift, expand, and contract under increased global temperatures.
Choose a temperature scenario below to see which threats will affect this species as warming increases. The same climate change-driven threats that put birds at risk will affect other wildlife and people, too.
A new study found significant declines in bird body sizes after analyzing decades of data collected by Chicago’s Field Museum.
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