Scarlet tanager

Scarlet tanager
Moulting adult male
Conservation status

Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Suborder: Passeri
Infraorder: Passerida
Superfamily: Passeroidea
Family: Cardinalidae
Genus: Piranga
Species: P. olivacea
Binomial name
Piranga olivacea
(Gmelin, 1789)
Synonyms

Piranga erythromelas

The scarlet tanager (Piranga olivacea) is a medium-sized American songbird. Until recently placed in the tanager family (Thraupidae), it and other members of its genus are now classified as belonging 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.

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) in length and from 25 to 30 cm (9.8 to 11.8 in) in wingspan.[3] 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 famous red coloration is more intense and deeply red than the males of two occasionally co-existing relatives, the northern cardinal and the summer tanager, both which lack the black wings of the scarlet and instead are an olive or brownish hued red on their wings. Females, on the other hand, 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 epithet olivacea ("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 non-breeding 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.[4]

Behavior

Scarlet tanagers eat ripe fruit when available, occasionally including ones, such as this orange half, that are set out by humans

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.[5][6] In winter, scarlet tanagers occur in the montane forest of the Andean foothills. Scarlet tanagers migrate to northwestern South America, passing through Central America around April, and again around October.[7] They begin arriving in the breeding grounds in numbers by about May and already start to move south again in mid-summer; by early October they are all on their way south.[8][9] The bird is an extremely rare vagrant to western Europe.

Scarlet tanagers are often out of sight, foraging high in trees, sometimes flying out to catch insects in flight and then returning to the same general perch, in a hunting style known as "sallying". Sometimes, however, they will also capture their prey on the forest floor. They eat mainly insects and any flying variety will readily be taken when common, such as bees, wasps, hornets, ants, and sawflies; moths and butterflies; beetles; flies; cicadas, leafhoppers, spittlebugs, treehoppers, plant lice, and scale insects; termites; grasshoppers and locusts; dragonflies; and dobsonflies. Scarlet tanagers also takes snails, earthworms and spiders. While summer tanagers are famous for this feeding method, when capturing bees, wasps and hornets, scarlet tanagers also rake the prey against a branch in order to remove their stingers before consumption.[10] Plant components of their diet consists of a wide variety of fruits that eaten mainly when insects are at population lows including: blackberries (Rubus allegheniensis), raspberries (R. ideaus), huckleberries (Gaylussacia sp.), juneberries and serviceberries (Amelanchier spp.), mulberries (Morus rubra), strawberries (Fragaria virginiana), and chokeberries (Aronia melanocarpa).[11][12]

Breeding

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 arrivals. 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.[4] 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 couple weeks old. If the nesting attempt is disturbed, apparently scarlet tanagers are unable to attempt a second brood as several other passerines can. In a study of 16 nests in Michigan, 50% of nests were successful in producing one or more fledglings.[13] In western New York, fledgling success increased from 22% in scattered patches of woods to as much as 64% in extensive, undisturbed hardwood forest.[6]

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.[14] Beyond failure due to brown-headed cowbirds (Molothrus ater) (see below), predation is the primary direct cause of nesting failures. In one study, 69-78% of nests were predated.[15] Recorded nest predators are primarily avian like blue jays (Cyanocitta cristata), common grackles (Quiscalus quiscula) and American crows (Corvus brachyrhynchos), although others like squirrels, chipmunks, raccoons (Procyon lotor) and snakes probably take a heavy toll as well as an occasional unlucky fledgling as do cats (Felis catus). Raptorial birds hunt and kill many scarlet tanagers from fledgling throughout their adult lives, including all three North American Accipiter species, Merlins (Falco columbarius), eastern screech owls (Megascops asio), barred owls (Strix varia), long-eared owls (Asio otus) and short-eared owls (Asio flammeus).[4][16][17]

These birds do best in the forest interior, where they are less exposed to predators and brood parasitism by the brown-headed cowbird. The cowbird lays its eggs in most any other passerines nest and the young often outcompete the young of the host bird and may cause failure and starvation. Some birds have evolved strategies to deal with cowbird parasitism, but the scarlet tanager, being a bird that evolved to breed in forest interior and not previously exposed to this, are helpless victims to brood parasitism. Where forest fragmentation occurs, which is quite widespread, the scarlet tanager suffers high rates of predation and brood parasitism in small forest plots and are 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 on a global scale tanagers are a plentiful species. Thus, the IUCN classifies the scarlet tanager as being of least concern.

References

  1. ↑ BirdLife International (2012). "Piranga olivacea". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
  2. ↑ Remsen, J. V., Jr., C. D. Cadena, A. Jaramillo, M. Nores, J. F. Pacheco, M. B. Robbins, T. S. Schulenberg, F. G. Stiles, D. F. Stotz, and K. J. Zimmer. Version [2009-04-02]. [A classification of the bird species of South America. American Ornithologists' Union.
  3. ↑ 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.
  4. ↑ 4.0 4.1 4.2 Mowbray, 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
  5. ↑ 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.
  6. ↑ 6.0 6.1 Roberts, C. and C. J. Norment. 1999. Effects of plot size and habitat characteristics on breeding success of Scarlet Tanagers. Auk 116:73-82.
  7. ↑ Herrera, Néstor; Rivera, Roberto; Ibarra Portillo, Ricardo & Rodríguez, Wilfredo (2006): Nuevos registros para la avifauna de El Salvador. ["New records for the avifauna of El Salvador"]. Boletín de la Sociedad Antioqueña de Ornitología 16(2): 1–19. [Spanish with English abstract] PDF fulltext
  8. ↑ Henninger, W.F. (1906). "A preliminary list of the birds of Seneca County, Ohio" (PDF). Wilson Bulletin 18 (2): 47–60.
  9. ↑ Ohio Ornithological Society (2004): Annotated Ohio state checklist.
  10. ↑ Grant, C. (1945). Drone bees selected by birds. Condor, 261-263.
  11. ↑ E.g. of Gumbo-limbo (Bursera simaruba). Trophis racemosa (Moraceae), and especially of Cymbopetalum mayanum (Annonaceae): Foster, Mercedes S. "The potential of fruiting trees to enhance converted habitats for migrating birds in southern Mexico". doi:10.1017/S0959270906000554.
  12. ↑ Mcatee, W. L. 1926. The relation of birds to woodlots in New York state. Roosevelt Wildl. Bull. no. 4.
  13. ↑ Prescott, K. W. 1965. The Scarlet Tanager (Piranga olivacea). N.J. State Mus. Invest. no. 2.
  14. ↑ Stevenson, H. M. and B. H. Anderson. 1994. The birdlife of Florida. Univ. Press of Florida, Gainesville.
  15. ↑ Brawn, J. D.; Robinson, S. K. (1996). "Source-sink population dynamics may complicate the interpretation of long-term census data". Ecology 77: 3–12. doi:10.2307/2265649.
  16. ↑ Hamerstrom Jr, F. N., & Hamerstrom, F. (1951). Food of young raptors on the Edwin S. George Reserve. The Wilson Bulletin, 16-25.
  17. ↑ Meng, H. (1959). Food habits of nesting Cooper's Hawks and Goshawks in New York and Pennsylvania. The Wilson Bulletin, 169-174.

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