BirdAnalyst
Species · Montana · BBS 2025 Release · 1966–2024

Warbling Vireo Population Trend in Montana

All statesForest birds

Warbling Vireo in Montana has surged: up 121% on the route-weighted index since 1970.

+121%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 →
56YearsYears 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 121% 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 stay roughly flat through 2029, near 8.7 (95% range 6.5–11). A 5-year backtest shows a typical error of ±11.1%, with 100% of held-out values landing inside the 95% band.

+9%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 →
8.7Projected 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 →
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 →
±11.1%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 stay roughly flat through 2029, near 8.7 (95% range 6.5–11). A 5-year backtest shows a typical error of ±11.1%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20258.46.311
20268.56.411
20278.66.411
20288.66.511
20298.76.511

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 →
Clancy5120232015
Fish Creek5020241995
Arlee4320241968
Wise River3820241993
Cramer Creek3420191995
Sula3320241978
Lima3320241994
Pryor Mtn.3320241995
Hebgen Lake3220242017
Logan Pass3220241980
Chestnut3120241968
Red Rock3020241978
Elliston2720241969
East Glacier Park2720242015
Noxon2620231995
Clinton2520241975
Whitefish Lake2320242016
Greenough2120041996
Painted Rock2020221992
Greenoagh 22020112005
Fort Logan1820242018
Woodman1620241968
Philipsburg1520242015
Freeman Creek1520162015
Maynard Coulee1520242017

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 2026-05-22.