One nice day in September, I walked with a few friends in a subalpine area with small shrub thickets scattered throughout a meadow of no-longer-blooming wildflowers. A subdued clucking sound in the brush caught our ears and we stopped to look.
A little family of about six well-grown willow ptarmigan chicks wandered out of the brush and into the meadow, heads down, busily searching for bugs, seeds, berries, buds, and catkins. The brown female was nearby, clucking gently and keeping watch. As they all searched and sampled whatever looked good, we noticed another bird, standing on a small rock not far away.
This bird was resplendent in a plumage of rich brownish red, with white legs and belly. He was overseeing the foraging efforts of his mate and chicks, alert for predators. He stood there like a proud papa wearing a cut-away coat with tails and white breeches. Very handsome! And the family was still intact, chicks shepherded by both parents.
Willow ptarmigan are unusual members of the taxonomic group of grouse: males participate in parental care until the chicks become independent in the fall. Males of all the other kinds of grouse are intent upon courting females and showing off to each other and have no role in chick-rearing.
In early spring, male willow ptarmigan begin to establish territories, which can be over ten acres in extent. Territory borders are defended vigorously. Neighboring males may march, rather peacefully, side by side along a shared border; and territories are advertised by vocalizations (the ‘rattling’ call) and flight displays. More intense competition involves charging at each other, knockdown-dragout fights, and long-distance chases, often well outside the area of contention. Females arrive a bit later than males, and they may be aggressive against other females.
Females are choosy when selecting mates. They like males with large red ‘combs’ over the eyes, large territories, and vigorous displays. Although sexually mature at age one, the yearlings are less likely than more experienced males to attract a female. A male courts a female by fanning tail and wings, strutting, stomping and bowing, and ‘waltzing’ around her with his fans facing her. If she likes what she sees, they form a pair. Most pairings are truly monogamous, with little extracurricular activity (unlike many other birds). If both members survive, the pair may stay together several years (annual survival in northern B. C. was reported to be roughly thirty to sixty percent (slightly higher for males than females).
Although the female builds the nest and does the incubation, the male guards her and the nest, sounding an alarm if a predator approaches. He tries to protect the family by distracting the predator: feigning injury, leading the predator away. An intensive defense includes loud vocalizations.
Females generally lay seven to nine eggs, sometimes as many as fourteen. During the egg-laying period, before incubation begins, females often leave the nest and go foraging. They commonly cover the eggs with grass or leaves while they are away. During three weeks of incubation, she covers the nest and eggs herself at least ninety percent of the time, seldom leaving to find food. Both male and female defend the eggs and, later, the chicks. A study in northern B. C. found that, on average, about fifty-four percent of females successfully raise at least some chicks; predation on eggs can be more serious than predation on chicks, but even so, about half the chicks that hatch don’t survive more than a few months.
Chicks can feed themselves soon after hatching and can regulate their own body temperatures quite well after a week or so. But the female broods even two-and three-week old chicks if the weather is cold and wet. Males sometimes brood, too, and if the female dies, he can rear chicks by himself. Chicks can fly at age ten to twelve days, and they move around together with the parents, often ranging beyond the territory borders. The family stays together until fall. Occasionally, parents may adopt chicks from another family.
As winter approaches, ptarmigan molt into the white winter plumage that camouflages them on snowy backgrounds. Not quite all-white—there are some black tail feathers. Come spring and the breeding season, male plumage turns reddish brown on head and neck, leaving the body white, while female plumage gradually turns brown (with white in the wings). As summer progresses, the reddish brown of the male spreads over the chest and back, leaving the belly (and most of the wings) white. That is why these birds are called red grouse in Scotland, and this was the plumage sported by the elegant fellow we saw.
All the birds will be white when winter comes. Winter plumage is denser than summer plumage and that, together with a seasonally greater metabolic tolerance of low temperatures and the habit of burrowing into the snow blanket, helps keep them warm.