BirdAnalyst
Species · Montana · BBS 2026 Release · 1966–2025

Pacific Wren Population Trend in Montana

All statesForest birds

Pacific Wren in Montana has surged: up 320% on the route-weighted index since 1971.

+320%Since 1971TrendPercent 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 →
23Routes 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 →
52YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Pacific Wren Trends in MontanaNotable 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 →

Pacific Wren has surged in Montana: up 320% on the route-weighted index since 1971.

Pacific Wren Population Forecast in Montana

If the recent trend holds, Pacific Wren in Montana is projected to rise about 149% by 2030 — from 0.25 in 2025 to a central estimate of 0.63 (95% range 0.11–1.2). A 5-year backtest shows a typical error of ±74.9%, with 100% of held-out values landing inside the 95% band.

+149%Change by 2030TrendPercent 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 →
0.63Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.11–1.295% 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 →
±74.9%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, Pacific Wren in Montana is projected to rise about 149% by 2030 — from 0.25 in 2025 to a central estimate of 0.63 (95% range 0.11–1.2). A 5-year backtest shows a typical error of ±74.9%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.600.071.1
20270.600.081.1
20280.610.091.1
20290.620.101.1
20300.630.111.2

Pacific Wren Survey Routes in Montana

Routes recording Pacific Wren in Montana.
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 →
Whitefish Lake1220242016
Skalkaho1219981992
St Regis720251983
Swan Lake520252015
Libby Dam420001988
Threemile Wa320241993
Arlee320251968
Woodman320251968
Skalkho-Rye320221999
Ninemile320221998
Logan Pass220251988
Cramer Creek220112005
Thompson Riv220241993
Painted Rock220191993
Noxon220221995
Kalispell120022002
Greenough120031996
Elevation Mt120222021
Clinton120081987
Inside Road120251990
Sula120121986
Greenoagh 2120082008
Fish Creek120241998

Pacific Wren Population Trend in Other States

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Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.