BirdAnalyst
Species · Colorado · BBS 2026 Release · 1966–2025

Yellow Warbler Population Trend in Colorado

All statesForest birds

Yellow Warbler in Colorado has held roughly steady: down 5% on the route-weighted index since 1970.

-5%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 →
144Routes 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 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 stay roughly flat through 2030, near 4.8 (95% range 1.6–8.1). A 5-year backtest shows a typical error of ±13%, with 100% of held-out values landing inside the 95% band.

-7%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 →
4.8Projected 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 →
1.6–8.195% 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 →
±13%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 stay roughly flat through 2030, near 4.8 (95% range 1.6–8.1). A 5-year backtest shows a typical error of ±13%, 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 →
20264.91.78.2
20274.91.68.2
20284.91.68.2
20294.91.68.1
20304.81.68.1

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
Aspen4120251979
Parlin4120251968
Castleton4120251988
Rifle Falls3520251998
Yellowjacket Pass3120251998
Arsenal 22320252016
Animas 22220252005
Stillwater Pass2120091998
Heeney 22120252025
Tarryall1720251988
Fox Creek1720251993
Steamboat L.1620251996
Douglas Pass1520241982
Doyleville1420251988
Ragged Mtn.1420251994
Cortez1320081988
Blackhead Pk1320251991
Pinos Creek1219901988
Walsenburg1220251994
Moon Pass1220252003
Alamosa1120251988
Cokedale1120251995
Heeney1120192017
Stillwater Pass 21120252010

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 2026-08-14.