This species breeds in mature deciduous woodlands, particularly where oaks are common. The range coincides with the Eastern Deciduous Forest Biome, from about 49 degrees N in southeast Manitoba to Nova Scotia, and south in this habitat to South Carolina in the east and Oklahoma in the west [Mowbray 1999 (BNA)]. Nests are usually in the outer horizontal branches of large deciduous trees (2-20+ m), though height may not be a controlling factor [Prescott 1965]. The breeding season diet consists of a wide variety of invertebrates and fruits [Prescott 1965]. There is no information from the winter range. Winter habitat is not well documented, primarily montane evergreen forests between 100 and 1,300 m [Stotz et al. 1996]. The winter distribution is from eastern Panama, south on the east slopes of the Andes to north Bolivia, and possibly into the western Amazon lowlands [Paynter 1995].
The migration habitat includes a wide variety of forest, forest edges, scrub, open woodlands and gardens [Mowbray 1999 (BNA)]. Scarlet Tanagers are nocturnal migrants, leaving wintering areas from mid-February to mid-March, peaking on the U.S. Gulf coast in early April and New England by mid-May [Mowbray 1999 (BNA)]. Fall migration is poorly documented, starting in mid to late-August in northern Vermont [Laughlin and Kibbe 1985], and peaking in mid-September in Massachusetts [Veit and Petersen 1993]. Migrants depart from the Gulf coast by mid-October and may reach South American wintering grounds by early November [Mowbray 1999 (BNA)].
Long-term Breeding Bird Survey trends are relatively stable, although significant decreases were noted from 1980-1996 in northern New England and all of eastern U.S. Cold, wet weather at the spring arrival may cause mortality, e.g. a 30% decline in New Hampshire breeders in 1974 [Zumeta and Holmes 1978]. Also Robinson et al. [1995] recorded 80%+ parasitism by cowbirds and 70% predation in highly fragmented forest landscapes in Illinois. This is considered a population sink, where not only do breeders fail to replace their own numbers, but surrounding areas of higher potential success may be drained of breeding birds.
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