Merlin

Willow Ptarmigan Life History

Habitat

Habitat Tundra

During the breeding season, Willow Ptarmigan inhabit subarctic and subalpine habitats where there is abundant shrubby vegetation, usually places below 6,000 feet elevation. At this season, they favor flat, moist areas as opposed to steep, dry slopes. Common plants are willow, birch, spruce, and fir; crowberry and blueberry are also present in some parts of the breeding range. Family groups forage along streams or marsh edges. In autumn, Willow Ptarmigan in western North America move upslope, often to sites above 6,000 feet, where they molt into their white winter plumage. These areas are drier and stonier than breeding habitats, to which they return after completing molt. In the central and eastern parts of Canada in autumn, Willow Ptarmigan (especially females and young of the year) migrate southward into the boreal forest for the winter, but there is much local variation in such movements.

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Food

Food Plants

Willow Ptarmigan have a simple diet of plant matter, primarily flower buds, catkins, leaves, twigs, berries, and seeds. In summer, they also eat whatever insects are available, both from the ground and low vegetation. Specific plant foods include willow, blueberry, bearberry, horsetail, birch, poplar, avens, Viburnum (arrowwood), and seeds of various grasses and sedges. Willow Ptarmigan forage slowly and deliberately, walking slowly and taking foliage with the sharp bill, gleaning insects, and plucking berries. They feed typically just after sunrise and in the late afternoon, but during the long days of summer, they feed throughout the day. Young birds eat much the same plant matter as adults.

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Nesting

Nest Placement

Nest Ground

Females probably select nest sites, which are on the ground among shrub thickets (willow, fir, or birch), often with overhanging vegetation.

Nest Description

The female makes a depression with her feet, lining it with moss, grass, leaves, and feathers. The interior of the nest averages about 7 inches across and about 4.7 inches deep.

Nesting Facts
Clutch Size:4-14 eggs
Number of Broods:1 brood
Egg Length:1.5-1.9 in (3.9-4.8 cm)
Egg Width:1.1-1.3 in (2.8-3.4 cm)
Incubation Period:21-23 days
Condition at Hatching:Completely covered with dense down, eyes open. Leave nest within six to 12 hours after the last egg hatches.
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Behavior

Behavior Foliage Gleaner

Willow Ptarmigan are highly territorial in spring. Males defend territories vigorously against other males, and once mated, females also defend the pair’s territory against other females. Territories vary from about 3 acres to as much as 20 acres. Females arrive in breeding areas about 2 weeks later than males and watch singly or in small groups as males display. To entice females, males perform elaborate courtship displays that involve fanning and flicking the tail, spreading the wings, bowing, parading, and drumming with the feet. Males also call and erect their red eye-combs, and females appear to select males with larger combs and more energetic displays. When rival males come into conflict, they may chase one another or perform a series of threat displays similar to courtship, with much calling. Pairs stay close to each other during courtship; males guard the females through incubation, which relatively few bird species do. Some males are polygynous (have multiple female partners), and in such cases, the second female defends a smaller territory within the male’s territory. Only females incubate. Willow Ptarmigan is the only grouse species in which the male stays with the female and brood to defend them, and the pair may be together as long as 7 months. After the young fledge, adults in some areas move upslope, to molt into winter plumage at higher elevations. In some cases, they return to breeding territories to feed until winter weather compels them to migrate southward or downslope. In North America, most Willow Ptarmigan pair with the same mate in consecutive breeding seasons.

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Conservation

Conservation Low Concern

Willow Ptarmigan is a common and widespread species. Its range is too far north for studies like the North American Breeding Bird Survey to track population trends. Partners in Flight estimates a global breeding population of 43 million and rates the species an 8 out of 20 on the Continental Concern Score, indicating it is a species of low conservation concern. Willow Ptarmigan are hunted for food in many parts of their range. They are sometimes killed when they strike powerlines; however, these factors do not appear to have significant impacts on the global population. As with many bird species that nest in subarctic and arctic habitats, climate change may have significant negative impacts on the habitats and thus populations of this species.

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Credits

Hannon, S. J., P. K. Eason and K. Martin. (1998). Willow Ptarmigan (Lagopus lagopus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, USA.

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