MacGillivray's Warbler    Oporornis tolmiei

Migratory Status: Neotropical migrant

PIF Population Estimate: 5 400 000

Percent of western hemisphere population breeding in boreal forest: <25%

PIF Maximum Detection Distance (m) : 125

Canadian BBS Population trend: -0.8 n.s. (-1.8 to 0.2)

Life History

The MacGillivray’s Warbler is a member of the genus Oporornis, which along with the Connecticut Warbler (O. agilis) and the Mourning Warbler (O. philadelphia), may form a superspecies complex. It was initially named Tolmie’s Warbler by John Kirk Townsend in honour of his close friend Dr. W. T. Tolmie, until John J. Audubon renamed the species after his close friend, Dr. W. MacGillivray, an act that remains controversial to this day. Some believe the former common name should be reinstated, since Tolmie was a more accomplished ornithologist and spent most of his time in the Pacific Northwest.

The MacGillivray’s Warbler is a relatively large wood warbler with an olive back, yellow breast, and prominent grey to indistinct brownish hood. It is distinguished from similar members of this genus by distinct whitish upper and lower eye-crescents (appearing as an incomplete eye ring, with breaks in front of, and behind, the eye) that are present in all plumages. The loud, albeit complex song, combined with its shy and elusive nature can make it a difficult species to locate in the field.

The continuous breeding range includes most of the mountainous regions of western North America, extending from southeast Alaska and the southern Yukon Territory, south to central California and New Mexico. Breeding populations at the southern limit of the breeding range are separated, especially in southern California, Arizona, and New Mexico. Local breeding populations occur in southeast Coahuila and southern Nuevo León, Mexico. The species winters primarily along the Pacific slope of Central America, from northern Mexico through Panama.

Reference(s)

Pitocchelli, J. 1995. MacGillivray's Warbler (Oporornis tolmiei), The Birds of North America Online, . A. Poole, Ed. Ithaca: Cornell Laboratory of Ornithology; Retrieved from The Birds of North America Online database: http://bna.birds.cornell.edu/bna/species/159