BirdAnalyst
Species · Alaska · BBS 2025 Release · 1966–2024

Willow Ptarmigan Population Trend in Alaska

All statesGeneralists

Willow Ptarmigan in Alaska has surged: up 87% on the route-weighted index since 1984.

+87%Since 1984TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
40Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
42YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Willow Ptarmigan Trends in AlaskaNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

Willow Ptarmigan has surged in Alaska: up 87% on the route-weighted index since 1984.

Willow Ptarmigan Population Forecast in Alaska

If the recent trend holds, Willow Ptarmigan in Alaska is projected to fall about 47% by 2029 — from 2.4 in 2024 to a central estimate of 1.3 (95% range 0.00–3.1). A 5-year backtest shows a typical error of ±97%, with 100% of held-out values landing inside the 95% band.

-47%Change by 2029TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology →
1.3Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–3.195% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±97%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
If the recent trend holds, Willow Ptarmigan in Alaska is projected to fall about 47% by 2029 — from 2.4 in 2024 to a central estimate of 1.3 (95% range 0.00–3.1). A 5-year backtest shows a typical error of ±97%, with 100% of held-out values landing inside the 95% band.19822029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20251.30.003.1
20261.30.003.1
20271.30.003.1
20281.30.003.1
20291.30.003.1

Willow Ptarmigan Survey Routes in Alaska

Routes recording Willow Ptarmigan in Alaska.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Red Dog8120241995
Cold Bay (Short)4519921984
Nome3120231993
Happy Valley2220241996
Teller1920241993
Savage1220241986
Salmon Lake520241993
Cold Bay520241993
Toklat420241982
Skagway420192014
King Salmon420241998
Pinoche Tral (Short)319841984
Kotzebue320242001
Selawik (Short)319871987
Utqiagvik220232021
Monahan220181983
Cape Nome220241993
Caribou Mtn.220231997
Galbraith L.220241995
St. Mary'S220141993
Kugarak (Short)219871987
Eagle120222007
Chiniak119981998
Paxson Lake119961991
Nabesna Road120161989

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.