GCBO Bird of the Month
Swainson’s Warbler
by Mike Williams
The Swainson’s Warbler, (Limnothlypis swainsoni), is named after the 19th century British naturalist William Swainson and was first named by John Audubon in 1834, but before that was described by John Abbott in 1801. It is a member of the family Parulidae, or the New World Warblers. The Swainson’s Warbler is the only member of the genus Limnothlypis, and has no sub-species. It breeds in the U.S. Southeast, including east Texas, and despite having no subspecies, the Swainson’s Warbler has a separate population that breed in the foothills of the Appalachian mountains, using rhododendron, a very different habitat than in the rest of the breeding range. The Swainson’s Warbler is migratory and Winters in Mexico and the Caribbean. These birds are generally uncommon but numbers do seem to be increasing even though habitat losses in its wintering grounds are of concern.
The Swainson’s Warbler is a shy reclusive bird more often heard than seen. It is typically found in swamps and canebrakes of the SE US but also in rhododendron bushes of the Appalachian Mountains. It is a ground and low bush/scrub forager living on a diet of insects, millipedes and spiders and when seen is usually turning over leaves with its bill in search of these.
Swainson’s Warblers are monogamous and lay 2 to 5 white eggs, (sometimes speckled brown), in a nest made of leaves, hair, pine needles and moss/roots. Their nests are typically low to the ground in scrub and bushes. Incubation is approximately 14 days and is carried out wholly by the female. The chicks fledge a further 2 weeks later and their lifespan is around 5-6 years, although some individuals can live 8 years or longer.
A larger new world warbler, Swainson’s is largely non-descript, being drab brown above and off-white below. It has a rufous crown and a dark eyeline. Its large heavy pale colored bill is distinctive. While often difficult to see, it is often heard in its range singing, sometimes almost continually in breeding season. Its song is a series of clear whistles and slurs “see see see whipoorwill”. It has various calls but usually a strong chip. Note males and females are very similar in appearance.
Interesting Facts:
  • A group of Warblers is called a bouquet, a fall, a wrench or a confusion.
  • Swainson, after whom is bird is named, was a famous, or more probably infamous, naturalist with radical views on classification. When his ideas fell out of favor (he supported the now defunct Quinarian classification system), he was ostracized by the scientific community and emigrated to New Zealand. Many species are named after him but none of his classifications are used today.
  • Swainson’s Warbler and its 2 distinct breeding populations are currently being studied, as little is understood about why these exist. The two populations are genetically identical and are not a result of subspeciation.


To download Mike Williams's photo of this cool bird, click HERE

To donate to us and our conservation work, click HERE