The identification of Sooty Grouse is generally straightforward within most of its range, where the only other grouse species is the Ruffed Grouse. The Ruffed Grouse is easily distinguished from female Sooty Grouse by its much smaller size, short but pronounced crest, barred underparts, and black subterminal band on the tail (lacking the pale terminal band that is present in Sooty Grouse). In some areas along the crest and eastern slopes of the Coast and Cascade Mountains, the distribution of the Sooty Grouse overlaps with that of the Spruce Grouse. Female Spruce Grouse are similar to female Sooty Grouse but are much smaller, shorter-necked, and shorter-tailed with less heavily-patterned underparts; the tail lacks the pale terminal band that is present in female Sooty Grouse.
The identification of this species along the eastern slopes of the Coast and Cascade Mountains is particularly complex due to the presence of the very similar, very closely related Dusky Grouse. The situation is even more complicated as a result of occasional hybridization between these two species in this area, but the discussion here will be restricted to pure individuals of each species. Both sexes of Sooty Grouse can be distinguished from Dusky Grouse (at least, those subspecies in B.C.) by the presence of a pale grayish terminal band on the tail. Dusky Grouse have no pale terminal band on the tail or, at best, very indistinct and narrow pale tips to the tail feathers. In addition, Sooty Grouse have 18 tail feathers (20 tail feathers in Dusky Grouse) that are more rounded at the tips and graduated, giving the tail a rounder (less squared) appearance when spread. Aside from these differences in tail shape and colour, and slight differences in overall colouration (female Sooty is somewhat darker and browner, female Dusky somewhat paler and greyer) the females of these two species are very similar.
The male Sooty Grouse is noticeably darker (sootier) than the male Dusky Grouse, which is a paler blue-grey colour overall, but the differences between the males of these two species are most evident during courtship displays. When displaying, the cervical apteria (neck pouches) of the male Sooty Grouse are inflated and appear as patches of bare, warty yellow skin on the side of the neck that are surrounded by a ruff of dark-tipped white feathers. In contrast, the displaying male Dusky Grouse inflates purplish-red cervical apteria that have less distinct warty tubercles on the skin and are surrounded by a ruff of more extensively white neck feathers. An additional behavioural difference between these two species is the tendency for male Sooty Grouse to display from an elevated perch (log, stump, low branch) or within the canopy of a coniferous tree, whereas the male Dusky Grouse typical displays from the ground. See ‘Vocalizations’ section for notes on differences in song between these two species.
| The male’s song consists of a series of six far-carrying, very deep hoots that often accelerate in tempo slightly towards the end and can be heard at distances of up to 300-500 m. The song is similar to the song of the male Dusky Grouse but is higher-pitched and much louder (song of Dusky Grouse rarely audible at distances greater than 50 m) and consists of six (rather than five) hoots. The male also sometimes gives a single whoot call during courtship with the female, and produces a low, growling call during antagonistic encounters. The female produces a precopulatory whinny during the breeding season, and often gives chicken-like clucking notes throughout the year. Source: Zwickel and Bendell (2005) |
Courtship
Courtship activities begin in late winter and early spring and continue through April and early May. Males regularly mate with multiple females over the course of the breeding season, but it is unknown whether females mate with more than one male. Males attract females to their territory through singing, which is usually done from an exposed perch such as a log, stump, low branch, or even from within the canopy of a small coniferous tree. Males also perform “flutter flights” along with singing which also serve to attract females to the territory. Once a female enters the male’s territory, he engages in an elaborate display that involves inflating the cervical apteria (chambers on the neck) to expose the bare yellow skin and surrounding rosette of white feathers, raising the yellow-orange combs (ridges of bare skin above the eyes), and raising and fanning the tail. If the female continues to approach the male, he will rush towards her while producing a series of whoot call notes and bobbing the head, often engaging in a brief chase. Once the female decides to mate, she will crouch and often produce a whinnying call in order to solicit copulation.
Nest
Nest construction occurs in April or May (earlier in the lowlands) and is completed entirely by the female. The nest is placed on the ground and consists of a shallow scrape ~17-23 cm across and ~4-5 cm deep that is lined with dead leaves, twigs, conifer needles, grasses, moss, bark, or rotted wood and often contains a few feathers; all materials are gathered from within the immediate vicinity of the nest. Almost all nests have some form of cover such as shrubs, ferns, grasses, forbs, logs, small trees, or a stump (sometimes as little as a single twig) above the nest for concealment.
Eggs
A clutch of (1) 4-8 (12) eggs is generally laid in late April or May (earlier in the lowlands), although some replacement clutches may be laid well into June or even July. Other than replacement clutches, this species is single-brooded The smooth eggs are pale pinkish-buff and are finely speckled and splotched with dark brown (rarely unmarked). Incubation is done solely by the female, and the incubation period is 25-28 days. Eggs are present in B.C. between late April and early August, although few clutches are reported later than June.
Young
The young are fully precocial upon hatching and leave the nest within the first day. They grow rapidly, are able to fly weakly within 6-7 days, and are capable of short, sustained flights at ~16 days of age. Newly-hatched chicks are reddish-brown on the upperparts and yellowish on the underparts and head, with black, blackish-brown, and reddish-brown mottling on the head and upperparts, two irregular and broken black stripes down the back, and two pale whitish bars across the wings; the short bill is pinkish to dark grey. Once they have left the nest, the female continues to travel with the brood until the late summer or fall (late August to late September), after which time the juveniles disperse and become independent. The young are able to feed themselves immediately upon hatching and rely on the female primarily for protection, cover (brooding), and for direction to productive foraging areas. Older chicks and juveniles feed progressively farther and farther from the female, but return to her side when alarmed or threatened. Dates for chicks and dependent juveniles in B.C. range from mid-May to late September.
Source: Campbell et al. (1990b); Madge and McGowan (2002); Zwickel and Bendell (2005)
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The diet of the Sooty Grouse is dominated by plant material throughout the year, although small amounts of animal material are consumed during the summer months. Conifer needles (particularly hemlock) form the bulk of the diet from September to May, and form nearly 100% of the diet during the winter months. Other plant materials that are important in the diet include berries (especially during the summer), fruits, seeds, leaves, buds, and flowers of a wide variety of shrubs and forbs. Also consumes tender tips of fern fronds (bracken fern, lady fern). Juveniles and some adults will consume insects (especially ants and grasshoppers) and other invertebrates during the breeding season. Most foraging occurs on the ground or in trees, with arboreal foraging most important during the winter when heavy snowpacks often hinder foraging on the ground. Like other grouse, this species regularly ingests gravel and small stones to aid with digestion, and can often be found along roadsides where it gathers grit.
Source: Baicich and Harrison (1997); Madge and McGowan (2002); Zwickel and Bendell (2005)
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