The Prairie Warbler (Setophaga discolor) is a rare fall visitor to New Brunswick and a bit more casual in spring. Most appear in coastal areas, mainly in the south. The first confirmed record was from Machias Seal Island in 1951. Today it is an annual visitor to Grand Manan Island. Individuals have been seen along the coast as far north as Miscou Island. It is rare to find it inland. This year there have been sightings of Prairie Warblers in at least 2 different places. The photos in this post are of a sighting in the Lorneville area, St. John County, on September 9.
The normal summer range of the Prairie Warbler is southern Ontario and central New England south to Oklahoma, the Gulf Coast, and Florida. It winters in southern Florida and in the tropics. Its preferred habitat is mixed pine-oak barrens, old pastures and scattered open scrub land. It also inhabitants mangrove swamps. Its name is a misnomer because it is not often found on the prairies.
The Prairie Warbler is a small warbler that wags its tail, much like its close relative, the Palm Warbler. It has a distinctive facial pattern as seen above. Note the yellow supercilium (line over the eye), dark eyeline, yellow crescent below the eye which is bordered by a black line. The upper parts are olive with reddish spots on the back. The under parts are bright yellow, a little paler yellow under the tail. There are bold black streaks on the sides which can become black spots on the sides of the throat. These contrast boldly with the bright yellow. Noting that and the distinctive facial pattern makes the identification of this species easy. The two wing bars are yellow, sometimes whitish. Females and non-breeding males are paler versions of the spring males. The less distinct facial pattern and some white around the eye would indicate the individual in the photo is an immature male or a female.
Although the Prairie Warbler is relatively easy to identify, you might have to rule out Pine Warbler or the Magnolia Warbler. The Pine Warbler shows no black on the head and the immature Magnolia Warbler has a yellow rump and a complete white eyering. The voice of the Prairie Warbler is distinctive. I remember the first time I heard it. I knew immediately what the bird was even though I did not see it at first. The song is buzzy, and a long series of zee, zee, zee which rises in pitch to the end.
The Prairie Warbler builds its nest usually low in a bush or small tree. The nest is made of grass and leaves and lined with hair and feathers. Four or five white eggs with brown spots are incubated for 11 to 14 days by the female. Prairie Warblers eat mainly insects which they catch by gleaning foliage, or catching them in mid-air by hovering. They will also feed on the ground. Female Prairie Warblers usually eat the shells of their eggs after hatching.
The population numbers of this species are declining. The main reasons are habitat loss and nest parasitism by cowbirds. The species was assigned 'vulnerable status' in Canada in 1985. That designation was later removed, in 1999. The Prairie Warbler was one of the early described species, being first described in 1809 by a French ornithologist, Louis Jean Pierre Vieillot.
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