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Species · BCR 2 · BBS 2025 Release · 1966–2024

Willow Ptarmigan In BCR 2

All regionsBCR 2Generalists

Willow Ptarmigan in BCR 2 has fallen sharply: down 73% on the route-weighted index since 1987.

-73%Since 1987TrendPercent 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 →
16Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
38YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 declinecomputed 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 fallen sharply in BCR 2: down 73% on the route-weighted index since 1987.

Forecast

If the recent trend holds, Willow Ptarmigan in BCR 2 is projected to fall about 12% by 2029 — from 4.3 in 2024 to a central estimate of 3.8 (95% range 0.00–15). A 5-year backtest shows a typical error of ±176.2%, with 100% of held-out values landing inside the 95% band.

-12%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 →
3.8Projected 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 →
0.00–1595% 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 →
±176.2%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 BCR 2 is projected to fall about 12% by 2029 — from 4.3 in 2024 to a central estimate of 3.8 (95% range 0.00–15). A 5-year backtest shows a typical error of ±176.2%, with 100% of held-out values landing inside the 95% band.19842029
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 →
20254.60.0016
20264.40.0015
20274.20.0015
20284.00.0015
20293.80.0015

Routes In BCR 2

Routes recording Willow Ptarmigan in BCR 2.
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 →
Cold Bay (Short)ALASKA451992
NomeALASKA312023
TellerALASKA192024
Cold BayALASKA52024
Salmon LakeALASKA52024
King SalmonALASKA42024
KotzebueALASKA32024
Selawik (Short)ALASKA31987
Cape NomeALASKA22024
St. Mary'SALASKA22014
Kugarak (Short)ALASKA21987
Katmai N.P.ALASKA12013
ChiniakALASKA11998
Kodiak 2ALASKA11997
CouncilALASKA12024
Togiak RiverALASKA11999

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