BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Willow Ptarmigan

PhasianidaeGame birdsLagopus lagopus

Willow Ptarmigan has surged: up 334% on the route-weighted index since 1984.

+334%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 →
40RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
42Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Willow Ptarmigan

The Willow Ptarmigan (Lagopus lagopus) is a North American member of the Pheasants, Grouse & Turkeys (Phasianidae). In this analysis it is grouped with the game birds.

Size
12–47 in long (30–120 cm) — a ground-dwelling game bird (typical for the family)
Habitat
Fields, brushland, prairie and the forest floor, where it forages and nests on the ground.
Diet
Seeds, grain, buds, leaves and insects gathered on the ground.
Range
Recorded on 40 Breeding Bird Survey routes across 1 state, most concentrated in the BCR 2.
Family
Phasianidae · Game birds

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

No notable trend signals for Willow Ptarmigan. See the full index history below.

Willow Ptarmigan Population Forecast

If the recent trend holds, Willow Ptarmigan is projected to fall about 34% by 2029 — from 0.07 in 2024 to a central estimate of 0.05 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±121.8%, with 100% of held-out values landing inside the 95% band.

-34%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 →
0.05Projected 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 →
0.00–0.1095% 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 →
±121.8%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 is projected to fall about 34% by 2029 — from 0.07 in 2024 to a central estimate of 0.05 (95% range 0.00–0.10). A 5-year backtest shows a typical error of ±121.8%, 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 →
20250.040.000.09
20260.040.000.09
20270.040.000.09
20280.050.000.09
20290.050.000.10

Where the Willow Ptarmigan Is Detected

BBS routes recording Willow Ptarmigan, sized by most recent count.

Willow Ptarmigan Population Trend by State

Willow Ptarmigan population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Alaska+87%198440

Willow Ptarmigan Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Willow Ptarmigan population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
BCR 2-73%198716
BCR 3+177%19975
BCR 4-54%198414
Northern Pacific Rainforest-19%20055

Willow Ptarmigan Conservation Status

Our route-weighted index shows it up about 334% since 1984.

Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.