MacGillivray's Warbler

Bird of the Month: MacGillivray's Warbler

By Andrew McCormick

Scientific Name: Oporornis tolmiei

Length 5.75 in

Wingspan 7.5 in

Weight 0.37 oz

AOU Band code MGWA

As with many of our western birds this warbler is named after human beings.  John James Audubon named it in honor of the Scottish ornithologist Wiliam MacGillivray who authored the 5-volume History of British Birds (1837-1851).  However, it was later learned that John Townsend (of Townsend’s Warbler and Townsend’s Solitaire) had named it for William Tolmei, a physician who worked for Hudson Bay Company.  So both men are remembered:  one in the scientific name (tolmiei) and the other in the common name.   Oporornis is combined from the Greek opora for autumn and ornis for bird, because this bird was seen more often in the fall migration (Holloway, 2003).  However, spring is an excellent time to find this bird in the Cascade Mountains.

MacGillivray’s Warbler is a western specialty that can be elusive.  It has been described as “skulking” by both John Dunn (1997) and Brian Bell (2006).  Spring migration brings these birds to our area with striking gray hoods which meet their bright yellow breast.  Their back is olive.  Separating this species from the very similar Mourning Warbler are the white arcs above and below the eyes.  The black lores connect across the forehead and seem to run into each eye prominently setting off the white arcs, which are always present in the MacGillivray’s.  The ranges of these two species overlap in central British Columbia.  The birds stay low in woodland brush and thickets of alder and willow and forage for a variety of beetles and caterpillars.   They build a nest of course grass, stems and bark between 2 and 5 feet from the ground in the vertical fork of branches.   They typically have four white eggs splotched with brown and incubate them for about 13 days.

The birds keep to the understory so when they do pop out onto the top of a shrub a birder can get a very nice view of them.   During migration a number of birds can be found in a small area.  There have been very good congregations of them near the West Summit Exit (52) off I-90.  Good areas to check are the shrubbery at the edges of the parking lot for the West Summit chairlifts and along a short trail on the north edge of the ski area going up the slope under the chair lift.  There is also a frontage road off SR-906 at Exit 53 that can be very good.  See A Birder’s Guide to Washington by Opperman (2003, p 269) for more details.  

The population of MacGillivray’s Warbler is fairly stable.  Their liking for undergrowth shrubs is fortunate for them as it is supported by new growth after logging has taken place.  With a little persistence this lovely bird with a very melodious song can be seen this month and make a nice addition to a day’s bird list.