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Species · Montana · BBS 2026 Release · 1966–2025

Warbling Vireo Population Trend in Montana

All statesForest birds

Warbling Vireo in Montana has surged: up 119% on the route-weighted index since 1970.

+119%Since 1970TrendPercent 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 →
83Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Warbling Vireo 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 →

Warbling Vireo has surged in Montana: up 119% on the route-weighted index since 1970.

Warbling Vireo Population Forecast in Montana

If the recent trend holds, Warbling Vireo in Montana is projected to rise about 26% by 2030 — from 6.9 in 2025 to a central estimate of 8.6 (95% range 6.5–11). A 5-year backtest shows a typical error of ±15.6%, with 100% of held-out values landing inside the 95% band.

+26%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 →
8.6Projected 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 →
6.5–1195% 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 →
±15.6%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, Warbling Vireo in Montana is projected to rise about 26% by 2030 — from 6.9 in 2025 to a central estimate of 8.6 (95% range 6.5–11). A 5-year backtest shows a typical error of ±15.6%, 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 →
20268.46.211
20278.56.311
20288.56.311
20298.66.411
20308.66.511

Warbling Vireo Survey Routes in Montana

Routes recording Warbling Vireo 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 →
Clancy5520252015
Fish Creek5020241995
Wise River4020251993
Chestnut3820251968
Woodman3720251968
Cramer Creek3420191995
Pryor Mtn.3420251995
Sula3320241978
Clinton3220251975
Lima2820251994
Arlee2720251968
Noxon2620231995
Whitefish Lake2320242016
Ninemile2120251993
Hebgen Lake2120252017
Greenough2120041996
Elliston2020251969
Red Rock2020251978
Painted Rock2020221992
Philipsburg2020252015
Greenoagh 22020112005
St Regis1920251977
Logan Pass1820251980
Freeman Creek1520162015
Threemile Wa1520251993

Warbling Vireo Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawareidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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