Erika and I saw these Yellow-rumped Warblers on 24 February 2022 at the Billy Frank Jr National Wildlife Refuge. When we moved to Olympia, we did not expect to see both races of this bird—the white-throated Myrtle Warbler and the yellow-throated Audubon’s Warbler. We have always thought of the Myrtle Warbler as an eastern bird, while Audubon’s are western. This assumption is basically correct, but the Myrtle Warbler does breed in Alaska and northern British Columbia. Thus the two races do occur north of us here in Washington and can be expected to migrate through the state.
Although the two races interbreed in the limited areas where they overlap, ornithologists still argue if they represent one or two species. The Audubon Society writes: “Even though the white-throated Myrtle and yellow-throated Audubon’s types interbreed where they meet, they’re very distinct genetically throughout the rest of their range. The evidence suggests that each is a full species.” The American Ornithological Society’s Checklist Committee has yet to agree.
