The Status and Occurrence of the Chestnut-sided Warbler (Setophaga pensylvanica) in British Columbia
by Rick Toochin and Don Cecile
Read the full aticle with photos on our Vagrant Birds page.
Introduction and Distribution
The Chestnut-sided Warbler (Setophaga pensylvanica) is a small passerine that breeds in Canada from eastern Alberta, through central Saskatchewan, southern Manitoba (except the southwest corner), and east through southern Ontario through southern Quebec into New Brunswick, Nova Scotia and locally in Newfoundland (Dunn and Garrett 1997). In the United States,the Chestnut-sided Warblers breeds from local parts of North Dakota, throughout the Great Lakes region east through New England to New Jersey, northern Delaware, south into the Appalachian Mountains south to northern Georgia (Curson et al. 1994). There are scattered breeding locations found in Iowa, northern Illinois, northern Indiana, and north western Ohio and in Colorado (Dunn and Garrett 1997). There are scattered summer records of Chestnut-sided Warbler to the south and west of their normal breeding range with isolated populations around the main breeding range south to Arkansas (Dunn and Garrett 1997).
The Chestnut-sided Warbler winters mainly in Central America from southern Nicaragua to Panama with some birds found in southern Mexico (Curzon et al. 1994). This species has been found in winter casually in South America in Ecuador and west to western Venezuela with records in the Greater Antilles (Curzon et al. 1994, Dunn and Garrett 1997). It is an uncommon to rare migrant in Bermuda with at least one winter record for the island (Dunn and Garrett 1997). It has been recorded in the winter on a couple of locations in the Lesser Antilles (Curzon et al. 1994, Dunn and Garrett 1997). The Chestnut-sided Warbler is a long distance migratory species that in the fall has a large movement of birds that start to move in late August and early September through the Appalachian Mountains and the Mississippi Valley (Dunn and Garrett 1997). These birds migrate by either following the shoreline of the Gulf of Mexico or crossing the Gulf of Mexico south to the Yucatan Peninsula on their way to spend the winter in Central America (Dunn and Garrett 1997). Other populations move south through Florida to winter in the Greater Antilles (Dunn and Garrett 1997). Spring migration begins in March as birds start to leave the wintering grounds (Dunn and Garrett 1997). The spring migration is greatly compressed with bird crossing directly over the Gulf of Mexico and emerging on the breeding grounds beginning in late April (Dunn and Garrett 1997).
The Chestnut-sided Warbler is a rare but increasing migrant vagrant along west coast. The species is annual in numbers in California with over one thousand records for the State, and it is no longer a review species by the California Bird Records Committee (Hamilton et al. 2007). In Oregon, the Chestnut-sided Warbler is no longer a review species by the Oregon Bird Records Committee with thirty-seven accepted State records (OFO 2012). In Washington, the Chestnut-sided Warbler is a review species by the Washington Bird Records Committee with twenty-one state records (Wahl et al. 2005, WBRC 2012). In British Columbia, the Chestnut-sided Warbler is a rare, almost annually occurring species, as there are fifty-eight Provincial records and one confirmed breeding record for the Province (Toochin et al. 2013a, Please see Table 1 & 2). There is one fall sight record for Alaska from Middleton Island (West 2008). The Chestnut-sided Warbler has occurred three times in Greenland, once in the fall in the Azores and in twice in the fall in Great Britain (Lewington et al. 1992, Dunn and Garrett 1997, Rodebrand 2012).