Willow ptarmigan

Name and taxonomy

Carl Linnaeus described the bird in 1758 and called it Tetrao lagopus. He gave the type locality as the alps of Europe, later narrowed to Sweden. The French zoologist Mathurin Jacques Brisson set up the genus Lagopus in 1760. Lagopus is the Latin word for a ptarmigan, and it began as a Greek term for hare-footed. The name probably points to the thick feathers that cover the toes.

Ornithologists list 15 subspecies spread across the northern hemisphere. The plumage shifts several times a year, so the taxonomy has always been muddled. The red grouse of Britain and Ireland was long counted as one of the subspecies. Several checklists now treat it as a species of its own, Lagopus scotica. Other English names for the species include willow grouse and large ptarmigan.

Evolution and relatives

The willow ptarmigan is one of four species in the genus Lagopus. Its nearest relatives are probably the rock ptarmigan and the white-tailed ptarmigan. The living bird has changed little from the one that walked the Pleistocene tundra. Fossils show that it ranged deep into continental Europe during the ice ages. Authors who accept fossil subspecies call those older birds L. l. noaillensis. They trace the line back to an earlier bird named Lagopus atavus.

About 10,000 years ago the last glaciation ended and the tundra moved north. The species followed its habitat and left continental Europe behind. Researchers have pulled its mitochondrial DNA out of permafrost in the Yukon. The bird crosses with black grouse and hazel grouse where their ranges meet. Rarer crosses involve the western capercaillie, the spruce grouse and the rock ptarmigan.

Appearance

This is a plump, ground-living bird with a deep chest and a fairly long neck. The bill is broad, the legs are short and feathered, and the tail is short and rounded. Adults measure 35 to 44 centimetres long, and the wingspan reaches 60 to 65 cm. Weight runs from 430 to 810 grams, and the average sits near 570 g. Feathers cover the toes as well as the legs, which is unusual among game birds.

In summer the male is marbled brown, with a rusty wash over the neck and breast. Bright red combs sit above his eyes and swell during the breeding season. The female wears a finer mottling of brown and ochre and has much smaller combs. By November both sexes are white, apart from the black outer tail feathers. The flight feathers stay white through every season. Red grouse in Britain and Ireland skip the white stage and stay dark reddish-brown.

Habitat and range

The willow ptarmigan has a circumboreal range that circles the top of the world. It breeds in northern Europe, across Siberia, and through Alaska and northern Canada. Newfoundland and Labrador and Quebec hold large Canadian populations. Norway, Sweden, Finland, Estonia, Latvia, Lithuania, Russia, Kazakhstan, Mongolia and China all lie in the range. GBIF holds occurrence records from 36 countries. iNaturalist carries 5,326 observations of the species.

The bird keeps to subalpine and subarctic ground rather than high bare rock. Typical cover is willow and alder thicket, open birch woodland, heather moor and damp tundra. Summer birds favour moist valleys, marshy tundra and the edge of the treeline. In winter the hens and young birds drop into valleys and thicker cover. Adult males usually hold their ground higher up. Most birds stay within 100 kilometres of their summer range, though some hens travel 160 km.

Diet and feeding

Adult willow ptarmigan are herbivores and take almost nothing but plant food. Summer meals include leaves, flowers, buds, grass shoots, seeds and berries. Blueberry, cranberry, lingonberry and crowberry all appear in the summer diet. As the insects fade in autumn, the birds take more berries, seeds and buds. Winter food narrows to willow buds and twigs, with some birch mixed in. Up to 94% of the winter diet can come from willow alone.

The birds dig through snow to reach buried shoots. In winter they feed twice a day, for roughly two hours each time. Feeding time grows as the northern daylight returns. Heavy browsing keeps the shrubs low, and one Alaskan study found 90% of reachable willow buds eaten. Chicks need protein, so they start on caterpillars, insects, flowers and seeds. Their caeca are not yet developed, so young birds handle plant food badly. Scottish red grouse eat heather instead, and it supplies up to 95% of their autumn food.

Behaviour and social life

Males claim breeding ground in April and May and drive off other males. Jumping and facing are the two common threat displays. In a jump, two or more birds spring about and beat their wings. In a face, two evenly matched birds stand head to head with their combs raised. A dominant bird may chase a rival far, and the loser is sometimes hurt or killed.

Willow ptarmigan walk and run far more than they fly. They creep low over snowfields and take off mainly to escape or to survey ground. In cold weather they dig burrows in the snow and roost inside them. The air in a burrow usually stays above the temperature at which the bird must burn energy. They bathe by fluffing up and flicking dust, sand or snow onto their backs.

Families gather into flocks by September, and winter birds feed and roost side by side. Close roosting probably helps the flock hold its heat. Winter flocks are nomadic and shift wherever food and shelter allow, from November to March. Family parties sometimes frolic, crouching low and leaping about with flapping wings.

Communication and senses

Observers have logged at least 11 different calls in this species. The voice is low and guttural, full of chuckles, clucks and sharp outbursts. A displaying male adds rattling and barking notes. Only males give the flight-song, the rattle, the kohwa and the aroo. Both sexes use koks, ko-ko-ko and krrow when they threaten, court or hold ground.

A hen purrs or moans to keep her chicks with her. Either parent hisses or moans when it defends the brood. Male calls carry more force and more modulation than the calls of hens. Like other birds, the species reads its world mostly through sight and hearing. The red combs above the eye work as a signal that a rival or a hen can see far off. Users of social media hear the call as awebo, and the nickname has spread widely.

Reproduction and life cycle

Males reach the breeding ground about two weeks before the hens. Courtship runs through tail-fanning, waltzing, rapid-stamping, bowing and head-wagging. In waltzing the male drapes his wings around the hen and circles her with short steps. A hen prefers a male with a wide territory, large combs and a keen display. She may leave, though, if the display turns too rough.

Most pairs are monogamous, and only 5 to 20% of males take a second hen. Between 83 and 86% of pairs reunite the next year when both birds survive. The pair scrapes a bowl in the ground and lines it with leaves, grass and feathers. The nest is 15 to 20 centimetres across and 8 to 16 cm deep, with one open side. A clutch holds 4 to 14 eggs, and incubation lasts 20 to 23 days in early summer.

A hatchling weighs about 15 grams and leaves the nest on the day it hatches. It stops needing its parents for warmth after 7 to 10 days. It can fly short distances at 10 to 12 days old. Young birds reach adult size by autumn and feed themselves at about 5 to 7 months. Both sexes can breed as yearlings, though not every young male wins ground or a mate.

The male guards the nest and the brood, and no other grouse gives that much care. A lone male can raise a brood after the hen dies. Unpaired males sometimes join a widowed hen and defend chicks that are not their own. The gain for such a male may be a mating chance later in the season.

Predators and threats

Predation is the chief cause of death, and starvation and weather matter far less. Birds rob more nests than mammals do. Arctic foxes, red foxes, gyrfalcons, golden eagles, snowy owls and ravens all take ptarmigan. Stoats, least weasels, pine martens, mink, lynx, wolverines and wolves hunt them too. Merlins and short-eared owls kill young red grouse in Britain.

A frightened bird crouches, lowers its head and holds still. A parent may walk away from the nest, or drag a wing as if it were broken. A quick moult keeps the plumage close to the colour of the ground. Fewer than 35% of chicks live to 11 months. Adult mortality runs from 60 to 72% a year.

Flukes, tapeworms, roundworms and skin parasites drain the birds and can kill them. Louping ill virus has killed as much as 78% of red grouse in a bad outbreak. Shrubs are spreading as the Arctic warms, which changes the winter food supply. Pollutants now reach even remote Arctic ground.

Population and conservation

The IUCN lists the willow ptarmigan as Least Concern. The world total is put at about 40 million birds. Numbers slip a little each year, but the range is huge and the habitat is remote. Populations swing on a cycle with a peak every 9 to 10 years. Weather and the quality of the food supply probably drive that cycle.

Regional lists tell a harder story in some places. Alberta rated the bird critically imperilled in 2009, unlike the rest of Canada. Estonia lists it as Endangered, and Finland lists it as Vulnerable. Britain holds roughly 250,000 breeding pairs of red grouse, and Ireland far fewer. Heather loss to forestry and grazing has cut Scottish numbers. Visitor pressure damages fragile northern ground that the bird depends on.

Relationship with humans

The willow ptarmigan is one of the most popular game birds of the north. Hunters shoot it across North America and Europe for sport and for the table. In Scotland and northern England the red grouse supports a whole rural industry. Shooting starts on 12 August each year, a date called the Glorious Twelfth. Beaters walk the moor and push the birds towards a line of hidden guns.

The number of grouse on a moor helps set what the land is worth. Estates burn the heather in patches, give the birds medicated grit and cull foxes and crows. The fall in red grouse numbers has cost income and work in the Central Highlands. Alaska made the willow ptarmigan its state bird in 1955. The bird does no harm to people, crops or property.

In culture and myth

The willow ptarmigan is probably familiar to every people of the far north. Norwegians call it lirype, Swedes dalripa, Finns riekko and the Sami rievssat. In Russian it is the white partridge, belaya kuropatka. Inupiaq speakers in Alaska know it as aqargiq. That name probably imitates the clucking call. Southern Lapland also names the species as its regional bird.

In Britain the red grouse appears in culture far more often than the northern form. It gave its shape to the emblem of the magazine British Birds. It also serves as the badge of a well known Scotch whisky. The Glorious Twelfth is a fixture of the British sporting calendar. London restaurants race each other to serve the first birds of the season.

The bird found a new audience in 2024 through short videos of its call. Listeners heard the Mexican Spanish phrase a huevo in the sound. The species now circulates online under the nickname awebo. The choice of a state bird in Alaska probably reflects how common the species is there.