Rock Ptarmigan ––A hardy grouse of the uplands
For the last two years, ptarmigan have been plentiful on the Seward Peninsula. They have been a boon to subsistence hunters, the wildlife that feeds on them, and anyone who enjoys watching their huge white winter flocks glide or scurry over the contours of the landscape. The ptarmigan’s comical calls never fail to inspire a smile and stir happy thoughts of springtime.
The Seward Peninsula is home to two of Alaska’s three ptarmigan species: the rock ptarmigan and the willow ptarmigan (see Birder’s Notebook in the May 4, 2023, edition of The Nome Nugget). Both of these hardy northern grouse are widespread residents of the peninsula.
The two species largely avoid competition by occupying different habitats. The larger willow ptarmigan is generally found in areas with taller shrubs or brushy tussock tundra. The rock ptarmigan is a bird of the uplands, where dwarf shrubs grow amidst drier, open, rocky tundra.
Rock ptarmigan are found all around the circumpolar north and nest at the northern-most reaches of land. Like willow ptarmigan, rock ptarmigan have interesting adaptations for life in the far north.
Their feet are heavily feathered to the tips of their toes. Like snowshoes, this increases the foot’s surface area, reducing sinking by about 50 percent. Feathered feet also provide warmth, and help ptarmigan dig burrows in the snow for roosting to escape harsh weather.
Like willow ptarmigan, rock ptarmigan camouflage themselves by changing their plumage with the season. In winter both males and females are dressed in white. The cocks have a distinctive black mask. Hens have no mask and differ from willow hens only by being smaller in size and having a smaller, narrower bill.
In early May female rock ptarmigan begin molting into their mottled brown summer attire. By the time they begin incubating in late May the hens are brown, except for white wing feathers. They are so well camouflaged on their tundra nests that even foxes are known to pass nearby without spotting them.
Male rock ptarmigan stay in their bright winter whites throughout courtship and breeding, long after their mates have turned brown. Their white plumage stands out like a beacon on the brown tundra and is thought to be attractive to females and a sign of vigor to territorial rivals.
Once incubation begins and the hen is no longer fertile, her mate begins dusting himself, soiling his white feathers and reducing his visibility while rapidly molting into his brown summer plumage.
Grouse have another interesting physical feature—their eye-combs. Both male and female rock ptarmigan have them, but female combs are small and are only raised when the hen is alarmed or defending a nest or chicks.
The large red combs above a male’s eyes are critical to a cock’s territorial defense and his sex appeal. They are erect during all courtship activities, and females are attracted to males with the largest, brightest combs.
Cocks display their combs prominently to other males when establishing and defending their territory. Usually, territorial disputes are resolved with ritualized threat displays on the ground and in the air.
Male rock ptarmigan establish territories in late April or early May, often returning to their previous claim. Hens arrive later, usually returning to the same general area. A hen then may or may not select her former territory and mate.
Rock ptarmigan courtship season on the upland tundra is full of elaborate displays and delightful low, rattling, staccato vocalizations.
Males are usually monogamous for the breeding season, but occasionally a cock may have two hens nesting on his territory. Female rock ptarmigan, unlike willow ptarmigan, are not aggressive towards other hens on the territory.
Both sexes scrape out shallow nest depressions in the dry tundra. The hen picks one and lines it with a few of her own feathers and bits of moss, lichens or grass.
Peak egg laying occurs in late May and early June. An average of seven eggs are laid at 24-to-30-hour intervals. The female begins incubating when the next-to-last egg is laid.
The eggs are cold-hardy and able to withstand temperatures below freezing for many days when left unattended, covered only by bits of vegetation before incubation begins.
The hen alone incubates, for an average of 21 days. Her mate guards the territory and accompanies her when she feeds. Unlike willow ptarmigan, the male rock ptarmigan usually does not help rear the young, and leaves the territory around the time of hatch.
Most chicks hatch during the last third of June. The hen leads her downy young away from the nest within a day of hatching, brooding them as needed to keep them warm.
For the first few days, the chicks live off nutrients stored in their bodies as they follow their mothers and learn how to find food. They grow quickly and within ten days the chicks double or triple their weight and can fly short distances.
Hens lead their broods to productive feeding areas where sometimes families mix together. Chicks typically stay with their mother until late August and become independent in 10 to 12 weeks.
During late June and July, after leaving their territories, males gather in flocks with other males and failed female breeders to feed and molt.
In September large roaming flocks form that include all ages and sexes. Flocking peaks in late September. Then flocks partially sort by sex as females and juveniles tend to shift to lower elevation wintering areas. Wintering flocks are nomadic. Their movements are driven by weather, snow conditions and food availability.
From October to March rock ptarmigan eat almost nothing but buds and catkins of dwarf birch. In April they add the previous year’s berries to their diet. When new leaves sprout in spring, their diet quickly shifts to plants, insects and spiders. In mid-August, when fresh berries and seeds are available, they are eaten.
Rock ptarmigan are a valued subsistence resource and important prey for a variety of wildlife in the region. Foxes, lynx and raptors, especially gyrfalcons, prey on adults. Eggs and chicks are vulnerable to gulls, jaegers, ravens and weasels.
Rock ptarmigan numbers fluctuate widely from year to year in a given location, but the species is common and widespread across their vast northern range. Reasons for their dramatic swings in abundance are not entirely understood. Numbers can change quickly in either direction, and weather conditions are thought to be an important driver. When conditions are favorable for chick production and overwinter survival, numbers can increase rapidly, or vice versa.
Since 2016, The Peregrine Fund has conducted spring surveys along Nome’s road system to assess the relative abundance of ptarmigan from year to year. In 2024 they tallied the second highest number of rock ptarmigan since 2016. Their highest count was in 2017.
The Peregrine Fund research on distribution of rock and willow ptarmigan in different habitats on the Seward Peninsula suggests that increasing shrubification may reduce rock ptarmigan habitat. While a reduction in open habitat may be detrimental for rock ptarmigan, willow ptarmigan may benefit from an increase in shrubby habitat, which they rely on for food and nesting.