The willow ptarmigan ( ; Lagopus lagopus) is a bird in the grouse tribe Grouse of the pheasant family Phasianidae. It is also known as the willow grouse. The willow ptarmigan breeds in birch and other forests and in northern Europe, the tundra of Scandinavia, Siberia, Alaska and Canada, in particular in the provinces of Newfoundland and Labrador and Quebec. It is the state bird of Alaska.
In the summer the birds are largely brown, with dappled plumage, while in the winter they are white with some black feathers in their tails. The species has remained little changed from the bird that roamed the tundra during the Pleistocene. Nesting takes place in the spring when clutches of four to ten eggs are laid in a scrape on the ground. The chicks are precocial and soon leave the nest. While they are young, both parents play a part in caring for them. The chicks eat insects and young plant growth while the adults are completely herbivorous, eating leaves, flowers, buds, seeds and berries during the summer and largely subsisting on the buds and twigs of willow and other dwarf shrubs and trees during the winter.
The taxonomy is confused, partly because of the complicated changes in plumage several times a year and the differing color and pattern of the summer plumage:
Fifteen subspecies are recognised:
The willow ptarmigan often hybridises with the black grouse ( Tetrao tetrix) and the hazel grouse ( Tetrastes bonasia) and occasionally with the western capercaillie ( Tetrao urogallus), the spruce grouse ( Falcipennis canadensis) and the rock ptarmigan ( Lagopus muta).
During the Pleistocene, the willow ptarmigan widely occurred in continental Europe. Authors who recognize paleosubspecies have named the Pleistocene willow ptarmigan L. l. noaillensis (though the older name medius might be the correct one). These marginally different birds are said to have Anagenesis from the earlier (Pliocene) Lagopus atavus into the present-day species L. lagopus. Pleistocene willow ptarmigan are recorded from diverse sites until the end of the Vistulian glaciation about 10,000 years ago, when the species, by then all but identical with the living birds, retreated northwards with its tundra habitat. Additionally, mitochondrial DNA of the willow ptarmigan has been recovered from permafrost in the Yukon Territory.
The willow ptarmigan can be distinguished from the closely related rock ptarmigan ( Lagopus muta) by its larger size and thicker bill and by the fact that it is not generally found above the tree line while the rock ptarmigan prefers more elevated, barren habitat. The summer plumage is browner and in the winter, the male willow ptarmigan lacks the rock ptarmigan's black stripe between the eyes and bill. The white-tailed ptarmigan ( Lagopus leucura) in North America is smaller, has a white tail and finely-barred greyer plumage and lives permanently above the tree line. The distinctive red grouse of the British Isles was once considered to be a subspecies. This moorland bird is reddish brown all over, except for its white feet.
The voice is low-pitched and guttural and includes chuckles, repeated clucking sounds, and expostulations. When displaying, the male makes rattles and barking noises.
In Alaska, the main dietary item of the adults at all times of year is such as the Alaska willow Salix alaxensis, with leaves being eaten in summer and buds, twigs and supplying the birds' main nutritional needs in winter and early spring. In the early twenty-first century, there has been an increase in shrub expansion in arctic Alaska that is thought to be greatly affecting the willow ptarmigan's winter diet. Because of the way they browse, ptarmigan help shape the landscape of the area. After heavy snowfalls, the birds cannot access the shorter shrubs as they are blanketed with snow, so they will eat the taller species that poke through. In one study it was found that 90% of the buds of the Alaska willow within their reach had been browsed. This will stunt the willows and create a feedback cycle extending through the entire ecosystem. However, in winters with below average snowfall, the browsing of ptarmigans will not have such a drastic effect as their feeding will be spread out across a range of lower plant species. It is also believed that the greening of parts of the Arctic is affecting willow ptarmigan populations by altering the shape and size of the shrubs they are able to feed on.
A small minority of male willow ptarmigan are polygynous but most are monogamous. They are assiduous at guarding both nest and mate, particularly early in the Egg incubation period and when the eggs are nearly ready to hatch. During this time, the greatest danger may be from Conspecificity. Although adult willow ptarmigans are , the newly hatched young also feed on . In most other species of grouse, only the female takes care of the young, but the male willow ptarmigan also helps with feeding the brood and protecting them. He may take over completely if the female dies. In particular, the male defends the young from Predation and both he and his mate can dive-bomb intruders or lure attackers away by pretending to have a broken wing. Nevertheless, the chicks face many dangers which range from attacks by or birds of prey, to getting separated from the rest of the brood, bad weather, and coccidiosis. Fewer than 35% of chicks survive to eleven months and only a minority of these reach maturity. Despite this, in favourable seasons, many juveniles may survive and the population of willow ptarmigan is prone to wide fluctuations in size. By September, families begin to form flocks. The females and young migrate to lower altitudes and may overwinter from their breeding grounds in wooded valleys and hilly country. The males also congregate in small groups but do not usually travel as far as the females.
Description
Distribution and habitat
Diet
Behavior
Cold adaptations
Status
Title bird
See also
External links