Rumors have been circulating for years now about a “split” in the Winter Wren complex. The only troglodytid to occur outside of the New World, this taxon exhibits noticeable morphological variation across its Holarctic range. Here in North America, studies have concentrated more and more on the differences in song between Winter Wrens in the East and their cousins in the West.

With the discovery in British Columbia of birds of each song type on adjacent territories, ornithologists looked for intermediates among the wrens in the contact zone–and they didn’t find any. “Genetically and behaviorally, the Tumbler Ridge wrens looked like separate species.”

With an eye to a future split, canny world birders are keeping track of where they see their Winter Wrens, what they look like and what they sound like. Who knows? One of these days, the field guides really may have to be revised, as this article suggests.