Swainson's warbler (''Limnothlypis swainsonii'') is a small

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

New World warbler The New World warblers or wood-warblers are a group of small, often colorful, passerine birds that make up the family Parulidae and are restricted to the New World. They are not closely related to Old World warblers or Australian warblers. Mos ...

. It is

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

, the only member of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

''Limnothlypis''. Swainson's warbler was named after William Swainson, an

English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national id ...

ornithologist Ornithology is a branch of zoology that concerns the "methodological study and consequent knowledge of birds with all that relates to them." Several aspects of ornithology differ from related disciplines, due partly to the high visibility and th ...

Description

Swainson's warblers are a small and rather nondescript songbird, though are fairly large for a New World warbler. Adults grow to in length and in weight. The wingspan averages . 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 Dimorphism or dimorphic may refer to: Science * Dimorphic root systems, plant roots with two distinctive forms for two separate functions * Sexual dimorphism, a phenotypic difference between males and females of the same species * Nuclear dimorp ...

, 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

canebrake A canebrake or canebreak is a thicket of any of a variety of '' Arundinaria'' grasses: '' A. gigantea'', '' A. tecta'' and '' A. appalachiana''. As a bamboo, these giant grasses grow in thickets up to 24 ft tall. ''A. gigantea'' is generally ...

s of the south-eastern United States. More rarely, they will also occur in

rhododendron ''Rhododendron'' (; from Ancient Greek ''rhódon'' "rose" and ''déndron'' "tree") is a very large genus of about 1,024 species of woody plants in the heath family (Ericaceae). They can be either evergreen or deciduous. Most species are nativ ...

thickets in the southern

Appalachian Mountains The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. The ...

. They are a migratory species, with part of the population migrating southeastwards to the

Greater Antilles The Greater Antilles ( es, Grandes Antillas or Antillas Mayores; french: Grandes Antilles; ht, Gwo Zantiy; jam, Grieta hAntiliiz) is a grouping of the larger islands in the Caribbean Sea, including Cuba, Hispaniola, Puerto Rico, Jamaica, ...

(where it overwinters in the Blue Mountains of Jamaica for example) and the other southwestwards to the

Yucatán Peninsula The Yucatán Peninsula (, also , ; es, Península de Yucatán ) is a large peninsula in southeastern Mexico and adjacent portions of Belize and Guatemala. The peninsula extends towards the northeast, separating the Gulf of Mexico to the north ...

region in winter.

Behavior

Breeding

This species begins breeding at about 10 months of age.Graves in Winker ''et al. 2000 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 The nesting season is the time of year during which birds and some other animals, particularly some reptiles, build nests, lay eggs in them, and in most cases bring up their young. It is usually in the spring. Bird conservation Bird conservat ...

. These birds live to as old as eight years.

Taxonomy

No subspecies are recognized. There appears to be some divergence between populations from

Arkansas Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, and Texas and Oklahoma to the west. Its name is from the ...

and others of the coastal plains. This does fit a pattern one would expect from

genetic drift Genetic drift, also known as allelic drift or the Wright effect, is the change in the frequency of an existing gene variant (allele) in a population due to random chance. Genetic drift may cause gene variants to disappear completely and there ...

, but there seem to be no

geographical Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, and ...

ecological Ecology () is the study of the relationships between living organisms, including humans, and their biophysical environment, physical environment. Ecology considers organisms at the individual, population, community (ecology), community, ecosy ...

barriers restricting

gene flow In population genetics, gene flow (also known as gene migration or geneflow and allele flow) is the transfer of genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalen ...

. Even during the last ice age, when average temperatures,

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hai ...

and

sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardise ...

s were lower, there seems to have been ample contiguous

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

. Clearly, some factor restricting gene flow is at work, but it is not presently known what it is. It is possible that the

subpopulation In statistics, a population is a set of similar items or events which is of interest for some question or experiment. A statistical population can be a group of existing objects (e.g. the set of all stars within the Milky Way galaxy) or a hypot ...

s conform to the different wintering areas.Winker ''et al.'' 2000 In some migrant birds it is known that the initial direction of the migration is set by fairly simple

hereditary Heredity, also called inheritance or biological inheritance, is the passing on of traits from parents to their offspring; either through asexual reproduction or sexual reproduction, the offspring cells or organisms acquire the genetic infor ...

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 Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight s ...

data is needed to determine whether this mechanism applies in Swainson's warbler.

References

*Winker, K., Graves, G. R. & Braun, M. J. (2000) Genetic differentiation among populations of a migratory songbird: ''Limnothlypis swainsonii''. '' J. Avian Biol.'' 31(3): 319–328. PDF fulltext

External links

- VIREO * ttp://www.flmnh.ufl.edu/index.php/download_file/view/1330/724/ Sounds- Florida Museum of Natural History {{Taxonbar, from=Q783095 Swainson's warbler Native birds of the Southeastern United States Swainson's warbler Swainson's warbler