Swainson's warbler

Swainson's warbler (Limnothlypis swainsonii) is a small species of New World warbler. It is monotypic, the only member of the genus Limnothlypis. Swainson's warbler was named after William Swainson, an English ornithologist.

Description
Swainson's warblers are a small and rather nondescript songbird, though are fairly large for a New World warbler. Adults grow to 12.5 - 16 cm in length and 11 - 20.5 g in weight. The wingspan averages 23 cm. They are a plain olive-brown above and pale yellow-white below. They have a whitish eyebrow stripe that runs above their eye, and the top of their head is a rusty brown. Unlike most other New World warblers that are mostly dimorphic, there is no difference in appearance between a male or female Swainson's warbler.

Distribution and habitat
Swainson's warblers are uncommon, mostly found in flooded swamplands and canebrakes of the south-eastern United States. More rarely, they will also occur in rhododendron thickets in the southern Appalachian Mountains. They are a migratory species, with part of the population migrating southeastwards to the Greater Antilles (where it overwinters in the Blue Mountains of Jamaica for example ) and the other southwestwards to the Yucatán Peninsula region in winter.

Breeding
This species begins breeding at about 10 months of age. Pairs form, and stake out and defend a territory for nesting. Nests are fairly large and bulky, constructed from moss, grass, and small leaves situated above ground in a tangle of tall reeds or vines. The female will lay between three and five eggs. The eggs are white and sometimes, but rarely, speckled with brown. Incubation is done by the female only and lasts for about 14 days, after which the eggs will hatch. The young leave the nest about 12 days later. It is not known how long pairs stay together, although once a pair-bond has been established they do not usually mate with other birds at least in the current nesting season. These birds live to as old as eight years.

Taxonomy
No subspecies are recognized. There appears to be some divergence between populations from Arkansas and others of the coastal plains. This does fit a pattern one would expect from genetic drift, but there seem to be no geographical or ecological barriers restricting gene flow. Even during the last ice age, when average temperatures, precipitation and sea levels were lower, there seems to have been ample contiguous habitat. Clearly, some factor restricting gene flow is at work, but it is not presently known what it is. It is possible that the subpopulations conform to the different wintering areas.

In some migrant birds it is known that the initial direction of the migration is set by fairly simple hereditary mechanisms. Offspring of pairs comprising birds of different subpopulations will, in such species, attempt to migrate into an intermediate direction. Such a course would lead a Swainson's warbler deep into the Caribbean where there are no wintering or even stopover points, and the bird would almost certainly perish. More research such as analyzing bird banding data is needed to determine whether this mechanism applies in Swainson's warbler.

Books

 * Brown, R. E., and J. G. Dickson. 1994. Swainson’s Warbler (Limnothlypis swainsonii). In The Birds of North America, No. 126 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists’ Union.

Thesis

 * Barrow WC, Jr. Ph.D. (1990). Ecology of small insectivorous birds in a bottomland hardwood forest. Louisiana State University and Agricultural & Mechanical College, United States, Louisiana.
 * de Cruz JB. Ph.D. (1996). Bird-habitat relations in regenerating forest of eastern North Carolina and Izabal, Guatemala. Duke University, United States, North Carolina.
 * Henry DR. Ph.D. (2005). Reproductive success and habitat selection of Swainson's warbler in managed pine versus bottomland hardwood forests. Tulane University, United States, Louisiana.
 * Strong AM. Ph.D. (1999). Effects of food abundance on non-breeding habitat quality for two species of ground-foraging neotropical migrant warblers. Tulane University, United States, Louisiana.
 * Thompson JL. Ph.D. (2005). Breeding biology of Swainson's warblers in a managed South Carolina bottomland forest. North Carolina State University, United States, North Carolina.

Articles
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 * Bassett-Touchell CA & Philip CS. (2006). Habitat Selection by Swainson's Warblers Breeding in Loblolly Pine Plantations in Southeastern Louisiana. Journal of Wildlife Management. vol 70, no 4. p. 1013.
 * Carrie NR. (1996). Swainson's Warblers nesting in early seral pine forests in East Texas. The Wilson Bulletin. vol 108, no 4. p. 802.
 * Casler CL & Este EE. (1997). Record of Swainson's Warbler (Limnothlypis swainsonii) in northern South America. Boletin del Centro de Investigaciones Biologicas Universidad del Zulia. vol 31, no 1. p. 95-98.
 * Conner RN & Dickson JG. (1997). Relationships between bird communities and forest age, structure, species composition and fragmentation in the West Gulf Coastal Plain. Texas Journal of Science. vol 49, no 3 SUPPL. p. 123-138.
 * Graves GR. (1992). A Case of Aggregated Nest Placement and Probable Polygyny in the Swainson's Warbler. Wilson Bulletin. vol 104, no 2. p. 370-373.
 * Graves GR. (1996). Censusing wintering populations of Swainson's Warblers: Surveys in the Blue Mountains of Jamaica. Wilson Bulletin. vol 108, no 1. p. 94-103.
 * Graves GR. (1998). Stereotyped foraging behavior of the Swainson's Warbler. Journal of Field Ornithology. vol 69, no 1. p. 121-127.
 * Graves GR. (2001). Factors governing the distribution of Swainson's Warbler along a hydrological gradient in Great Dismal Swamp. Auk. vol 118, no 3. p. 650-664.
 * Graves GR. (2002). Habitat characteristics in the core breeding range of the Swainson's Warbler. Wilson Bulletin. vol 114, no 2. p. 210-220.
 * Heckscher CM. (2000). Forest-dependent birds of the Great Cypress (North Pocomoke) Swamp: Species composition and implications for conservation. Northeastern Naturalist. vol 7, no 2. p. 113-130.
 * Heckscher CM & McCann JM. (2006). Status of Swainson's warbler on the delmarva peninsula. Northeastern Naturalist. vol 13, no 4. p. 521-530.
 * Heltzel JM & Leberg PL. (2006). Effects of selective logging on breeding bird communities in bottomland hardwood forests in Louisiana. Journal of Wildlife Management. vol 70, no 5. p. 1416-1424.
 * Kirkconnell A, Wallace GE & Garrido OH. (1996). Notes on the status and behavior of the Swainson's Warbler in Cuba. Wilson Bulletin. vol 108, no 1. p. 175-178.
 * Lanham JD & Miller SM. (2006). Monotypic nest site selection by Swainson's Warbler in the mountains of South Carolina. Southeastern Naturalist. vol 5, no 2. p. 289-294.
 * Miller SM. (2003). First report of a double-brooded Swainson's Warbler. Wilson Bulletin. vol 115, no 1. p. 94-95.
 * Peters KA, Lancia RA & Gerwin JA. (2005). Swainson's warbler habitat selection in a managed bottomland hardwood forest. Journal of Wildlife Management. vol 69, no 1. p. 409-417.
 * Revels MR & Whitworth TL. (2005). First record of Swainson's Warbler parasitism by Protocalliphora blow fly larvae. Wilson Bulletin. vol 117, no 2. p. 199-200.
 * Rimmer CC, Townsend JM, Townsend AK, Fernandez EM & Almonte J. (2005). Avian diversity, abundance, and conservation status in the Macaya Biosphere Reserve of Haiti. Ornitologia Neotropical. vol 16, no 2. p. 219-230.
 * Sallabanks R, Walters JR & Collazo JA. (2000). Breeding bird abundance in bottomland hardwood forests: Habitat, edge, and patch size effects. Condor. vol 102, no 4. p. 748-758.
 * Somershoe SG, Hudman SP & Chandler CR. (2003). Habitat use by Swainson's Warblers in a managed bottomland forest. Wilson Bulletin. vol 115, no 2. p. 148-154.
 * Strong AM. (2000). Divergent foraging strategies of two Neotropical migrant warblers: Implications for winter habitat use. Auk. vol 117, no 2. p. 381-392.
 * Strong AM & Sherry TW. (2001). Body condition of Swainson's Warblers wintering in Jamaica and the conservation value of Caribbean dry forests. Wilson Bulletin. vol 113, no 4. p. 410-418.
 * Thomas BG, Wiggers EP & Clawson RL. (1996). Habitat selection and breeding status of Swainson's warblers in southern Missouri. Journal of Wildlife Management. vol 60, no 3. p. 611-616.
 * Wiedenfeld DA & Wiedenfeld MG. (1995). Large kill of neotropical migrants by tornado and storm in Louisiana, April 1993. Journal of Field Ornithology. vol 66, no 1. p. 70-80.
 * Winker K, Glenn TC & Graves GR. (1999). Dinucleotide microsatellite loci in a migratory wood warbler (Parulidae: Limnothlypis swainsonii) and amplification among other songbirds. Molecular Ecology. vol 8, no 9. p. 1553-1556.
 * Winker K, Weiss SA, Trejo JL & Escalante P. (1999). Notes on the avifauna of Tabasco. Wilson Bulletin. vol 111, no 2. p. 229-235.