Wings of Thunder
Andrew’s recent post on Spruce Grouse sounds made this YouTube video into a particularly nice find. Shot by birding guide Khanh Tran in Washington state, it documents the double wing-clap display of the “Franklin’s” subspecies of the Spruce Grouse, which is the form found in the Pacific Northwest, north to central British Columbia and Alberta. The video will play in high resolution by default; I recommend clicking on the fullscreen icon. At the end, the wing-clap portion of the video is replayed in slow motion, and appears to show that the bird makes the sound by clapping its wings together above its back as it descends:
These wing-claps, aptly compared to gunshots in the Sibley guide, have never been documented in the widespread “Taiga” Spruce Grouse (subspecies canadensis). Most female grouse are thought to be extremely picky about their mates’ displays; males that don’t exactly match their expectations may not get a second look. Thus, display differences are thought to contribute to reproductive isolation of a couple of other closely related grouse species (Gunnison vs. Greater Sage-Grouse and Dusky vs. Sooty Grouse). The presence or absence of a couple of loud wing-claps seem like a reasonable mechanism for separating “Franklin’s” from “Taiga” Spruce Grouse.
Compare the above to this excellent (but lower-resolution) video from northern Minnesota that manages to capture, I think, all the displays of a nominate “Taiga” Spruce Grouse, including all the ones Andrew posted about. Note the similarity of the display flight as the male comes down from his tree perch — he “stalls out” much like the Franklin’s does and changes wingbeat speed, but resists all temptation to wing-clap. Instead he makes the much fainter “drumming” recorded by Andrew, which is essentially inaudible in this video.
If that video didn’t satisfy your thirst for watching “Taiga” Spruce Grouse, check out the sequels (1 2 3).
Very little information on the display of Franklin’s Grouse is easily available; Khanh Tran’s video appears to be the only one of its kind online. The Macaulay Library has a fairly extensive collection of Spruce Grouse recordings (both audio and video), but they all apparently pertain to the Taiga form. Although Franklin’s and “Taiga” Spruce Grouse were considered separate species at one point, they were lumped in the mid-20th century due to reports of hybridization and introgression in their contact zone in British Columbia and Alberta. As far as I can tell, no new information on this contact zone has surfaced in the scientific literature for more than fifty years, so there’s not much I can say about it. However, molecular phylogenies of the grouse by Gutierrez et al. (2000) and Drovetski (2002) both provided genetic evidence for a split of Spruce Grouse, and David Sibley recently listed it as one of the 10 most likely upcoming splits. But the group hasn’t been as well-studied as the Blue Grouse complex (now split again into Dusky and Sooty Grouse), so the checklist committee may want to reserve judgment for now.
Meanwhile, recordists wanting to make a difference in taxonomic research might schedule a trip to that legendary contact zone in Alberta and northern BC!