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

Yellow Warbler Population Trend in Colorado

All statesForest birds

Yellow Warbler in Colorado has held roughly steady: down 9% on the route-weighted index since 1970.

-9%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 →
143Routes 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 Yellow Warbler 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 →

No notable trend signals for Yellow Warbler in Colorado. See the full index history below.

Yellow Warbler Population Forecast in Colorado

If the recent trend holds, Yellow Warbler in Colorado is projected to rise about 16% by 2029 — from 4.2 in 2024 to a central estimate of 4.8 (95% range 1.5–8.1). A 5-year backtest shows a typical error of ±20%, with 100% of held-out values landing inside the 95% band.

+16%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 →
4.8Projected 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 →
1.5–8.195% 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 →
±20%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, Yellow Warbler in Colorado is projected to rise about 16% by 2029 — from 4.2 in 2024 to a central estimate of 4.8 (95% range 1.5–8.1). A 5-year backtest shows a typical error of ±20%, 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 →
20254.91.68.2
20264.91.68.2
20274.91.68.2
20284.91.68.2
20294.81.58.1

Yellow Warbler Survey Routes in Colorado

Routes recording Yellow Warbler 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 →
Yampa4520231969
Castleton4520241988
Aspen4020241979
Ragged Mtn.3020191994
Yellowjacket Pass2620241998
Stillwater Pass2120091998
Buford1820241970
Animas 21720212005
Douglas Pass1520241982
Cheesman Lk1520241969
Parlin1520231968
De Beque1520241992
Blackhead Pk1420211991
Moon Pass1420242003
Cortez1320081988
Pinos Creek1219901988
Walden1120241990
Doyleville1120241988
Alamosa1120241988
Paonia1120241992
Heeney1120192017
Dolores1019871968
Fox Creek1020241993
Weston Pass1020001994
Cortez 21020172009

Yellow Warbler Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniaconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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