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Species · Montana · BBS 2026 Release · 1966–2025

Nashville Warbler Population Trend in Montana

All statesForest birds

Nashville Warbler in Montana has surged: up 448% on the route-weighted index since 1981.

+448%Since 1981TrendPercent 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 →
46YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Nashville Warbler 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 →

No notable trend signals for Nashville Warbler in Montana. See the full index history below.

Nashville Warbler Population Forecast in Montana

If the recent trend holds, Nashville Warbler in Montana is projected to fall about 21% by 2030 — from 0.24 in 2025 to a central estimate of 0.19 (95% range 0.06–0.32). A 5-year backtest shows a typical error of ±34.2%, with 80% of held-out values landing inside the 95% band.

-21%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 →
0.19Projected 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 →
0.06–0.3295% 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 →
±34.2%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, Nashville Warbler in Montana is projected to fall about 21% by 2030 — from 0.24 in 2025 to a central estimate of 0.19 (95% range 0.06–0.32). A 5-year backtest shows a typical error of ±34.2%, with 80% of held-out values landing inside the 95% band.19752030
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 →
20260.180.050.31
20270.180.050.31
20280.180.050.32
20290.190.060.32
20300.190.060.32

Nashville Warbler Survey Routes in Montana

Routes recording Nashville Warbler 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 →
Arlee620251984
Fish Creek620241996
St Regis420251980
Ninemile420251993
Noxon420232000
Libby Dam320241983
Threemile Wa320252010
Victor220212010
Cramer Creek220182017
Woodman220251975
Lima220011999
Kalispell120252015
St Mary119891989
Elevation Mt120182018
Clinton119841981
Sula119901987
Skalkho-Rye120222018
Swan Lake120242017
Greenoagh 3120222018
Thompson Riv120241996
Pagil Gulch120152015
Painted Rock119961992
Wise River120121993

Nashville Warbler Population Trend in Other States

californiaconnecticutidahomainemarylandmassachusettsmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-dakotaoregonpennsylvaniarhode-islandvermontvirginiawashingtonwest-virginiawisconsin

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