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

Warbling Vireo Population Trend in Colorado

All statesForest birds

Warbling Vireo in Colorado has surged: up 332% on the route-weighted index since 1970.

+332%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 →
109Routes 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 ColoradoNotable 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 Colorado: up 332% on the route-weighted index since 1970.

Warbling Vireo Population Forecast in Colorado

If the recent trend holds, Warbling Vireo in Colorado is projected to stay roughly flat through 2029, near 12 (95% range 8.7–15). A 5-year backtest shows a typical error of ±12.5%, with 100% of held-out values landing inside the 95% band.

+6%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 →
12Projected 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 →
8.7–1595% 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 →
±12.5%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 Colorado is projected to stay roughly flat through 2029, near 12 (95% range 8.7–15). A 5-year backtest shows a typical error of ±12.5%, 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 →
2025118.215
2026118.315
2027128.415
2028128.615
2029128.715

Warbling Vireo Survey Routes in Colorado

Routes recording Warbling Vireo in Colorado.
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 →
Haycamp Mesa7920241998
Dolores Riv7620241988
Fox Creek6120241993
Mcphee Res.6020241996
Dunckley Pas5520241992
Aspen4220241979
Owl Creek Pass4220241998
Moon Pass3920241998
Uncompahgre3320241988
Groundhog Rs3320241992
Baxter Pass3220241994
Flattops3120191992
Stillwater Pass3120091999
Cheesman Lk3020241969
Ragged Mtn.3020191994
Lake City 22820242016
Castleton2720241988
Guanella Pas2720241992
Thomasville2620181992
Lizard Head Pass2620242001
Nucla2520241999
Marshall Pas2420191995
Comanche Pk2320241994
Cochetopa Pass2320241998
Wilson Creek2220241990

Warbling Vireo Population Trend in Other States

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

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