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The scarlet tanager (Piranga olivacea) is a medium-sized Americansongbird. Until recently, it was placed in the tanagerfamily (Thraupidae), but it and other members of its genus are now classified as belonging to the cardinal family (Cardinalidae).[2] The species' plumage and vocalizations are similar to other members of the cardinal family, although the Piranga species lacks the thick conical bill (well suited to seed and insect eating) that many cardinals possess. The species resides in thick deciduous woodlands and suburbs.
Etymology
The genus name Piranga is from TupiTijepiranga, the name for an unknown small bird, and the specific olivacea is from Neo-Latinolivaceus, "olive-green".[3]
Description
The scarlet tanager, a mid-sized passerine, is marginally the smallest of the four species of Piranga that breed north of the Mexican border. It can weigh from 23.5 to 38 g (0.83 to 1.34 oz), with an average of 25 g (0.88 oz) during breeding and an average of 35 g (1.2 oz) at the beginning of migration. Scarlet tanagers can range in length from 16 to 19 cm (6.3 to 7.5 in) and from 25 to 30 cm (9.8 to 11.8 in) in wingspan.[4] Adults of both sexes have pale, horn-colored, fairly stout, and smooth-textured bills. Adult males are crimson-red with black wings and tail. The male's coloration is intense and deeply red, similar but deeper in shade than the males of two occasionally co-existing relatives, the northern cardinal and the summer tanager, both which lack black wings. Females are yellowish on the underparts and olive on top, with yellow-olive-toned wings and tail. The adult male's winter plumage is similar to the female's, but the wings and tail remain darker. Young males briefly show a more complex, variegated plumage intermediate between adult males and females.
The somewhat confusing specific epithetolivacea ("the olive-colored one") was based on a female or immature specimen rather than erythromelas ("the red-and-black one"), which authors attempted to ascribe to the species throughout the 19th century (older scientific names always takes precedence, however).
Female, immature, and nonbreeding males may be distinguished from the same ages and sexes in summer tanagers, which are more brownish overall, and western tanagers, which always have bold white bars and more yellowish undersides than scarlet tanagers. The song of the scarlet tanager sounds somewhat like a hoarser version of the American robin's and is only slightly dissimilar from the songs of the summer and western tanagers. The call of the scarlet tanager is an immediately distinctive chip-burr or chip-churr, which is very different from the pit-i-tuck of the summer tanager and the softer, rolled pri-tic or prit-i-tic of western tanager.[5]
Behavior
Their breeding habitat is large stretches of deciduous forest, especially with oaks, across eastern North America. They can occur, with varying degrees of success, in young successional woodlands and occasionally in extensive plantings of shade trees in suburban areas, parks, and cemeteries. For a viable breeding population, at least 10 to 12 hectares of forest are required.[6][7] In winter, Scarlet tanagers migrate to the montane forest of the Andean foothills of northwestern South America, passing through Central America around April, and again around October.[8] They begin arriving in their breeding grounds in numbers by about May and already start to move south again in midsummer; by early October, they are all on their way south.[9][10] The bird is an extremely rare vagrant to Western Europe.
Male scarlet tanagers reach their breeding ground from mid-May to early June. Females generally arrive several days to a week later. Nest building and egg laying both occur usually in less than two weeks after the adults arrive. The clutch is usually four eggs, occasionally from three to five and exceptionally from one to six eggs may be laid. The eggs are a light blue color, often with a slight greenish or whitish tinge. Incubation lasts for 11 to 14 days. Hatching and fledging are both reached at different points in summer depending on how far north the tanagers are breeding, from June-early July in the southern parts of its breeding range to as late as August or even early September in the northernmost part of its range.[5] The average weight at hatching is 3.97 g (0.140 oz), with the nestlings increasing their weight to 20–22 g (0.71–0.78 oz) by 10 days, or 70% of the parent's weight. The young leave the nest by 9–12 days of age and fly capably by the time they are a few weeks old. If the nesting attempt is disturbed, scarlet tanagers apparently are unable to attempt a second brood, as several other passerines can. In a study of 16 nests in Michigan, 50% were successful in producing one or more fledglings.[16] In western New York, fledgling success increased from 22% in scattered patches of woods to as high as 64% in extensive, undisturbed hardwood forest.[7]
Threats and status
Exposure and starvation can occasionally kill scarlet tanagers, especially when exceptionally cold or wet weather hits eastern North America. They often die from collisions with man-made objects including TV and radio towers, buildings and cars.[17] Beyond failure due to brood parasitism of brown-headed cowbirds (Molothrus ater), predation is the primary direct cause of nesting failures. In one study, 69–78% of nests were preyed upon.[18] Recorded nest predators are primarily avian like blue jays (Cyanocitta cristata), common grackles (Quiscalus quiscula) and American crows (Corvus brachyrhynchos), although others such as squirrels, chipmunks, raccoons (Procyon lotor), domestic cats (Felis catus), and snakes take a heavy toll. Raptorial birds hunt and kill many scarlet tanagers from fledgling throughout their adult lives, including all three North AmericanAccipiter species, merlins (Falco columbarius), and owls, including eastern screech owls (Megascops asio), barred owls (Strix varia), long-eared owls (Asio otus), and short-eared owls (Asio flammeus).[5][19][20]
Scarlet tanagers birds do best in the forest interior, where they are less exposed to predators and brood parasitism by the brown-headed cowbird. Being a bird that evolved to breed in forest interior and not exposed to the brown cowbird prior to habitat fragmentation, scarlet tanagers have not evolved any defensive strategies to cope with it. Where forest fragmentation occurs, which is quite widespread, the scarlet tanager suffers high rates of predation and brood parasitism in small forest plots and is often absent completely from plots less than a minimum size. Their nests are typically built on horizontal tree branches. Specifically, their numbers are declining in some areas due to habitat fragmentation, but the IUCN still classifies the scarlet tanager as being of least concern.
^7.del Hoyo, J., Elliott, A. and Christie, D.A. (2011). Handbook of the Birds of the World. Volume 16: Tanagers to New World Blackbirds. Lynx Edicions, Barcelona.
^ abcMowbray, Thomas B. (1999). Scarlet Tanager (Piranga olivacea), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/479
^Robbins, C.S., D.K. Dawson, and B.A. Dowell (1989). Habitat area requirements of breeding forest birds of the Middle Atlantic states. Wildl. Monogr. 103.
^ abRoberts, C. and C.J. Norment (1999). Effects of plot size and habitat characteristics on breeding success of Scarlet Tanagers. Auk 116:73-82.
^Herrera, Néstor; Rivera, Roberto; Ibarra Portillo, Ricardo & Rodríoguez, Wilfredo (2006): Nuevos registros para la avifauna de El Salvador. ["New records for the avifauna of El Salvador"]. Boletín de la Sociedad Antioqueña de Ornitología16(2): 1–19. [Spanish with English abstract] PDF fulltext
^Mcatee, W.L. (1926). The relation of birds to woodlots in New York State. Roosevelt Wildlife Bulletin no. 4.
^Prescott, K.W. (1965). "The Scarlet Tanager (Piranga olivacea)." N.J. State Mus. Invest. no. 2.
^Stevenson, H.M. and B.H. Anderson. (1994). The birdlife of Florida. Univ. Press of Florida, Gainesville.
^Brawn, J. D.; Robinson, S. K. (1996). "Source-sink population dynamics may complicate the interpretation of long-term census data". Ecology. 77 (1): 3–12. doi:10.2307/2265649. JSTOR2265649.
^Hamerstrom Jr, F.N., & Hamerstrom, F. (1951). "Food of young raptors on the Edwin S. George Reserve." The Wilson Bulletin 16–25.
^Meng, H. (1959). "Food habits of nesting Cooper's Hawks and Goshawks in New York and Pennsylvania." The Wilson Bulletin 169-174.