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Species · Colorado · BBS 2025 Release · 1966–2024

Orange-crowned Warbler Population Trend in Colorado

All statesForest birds

Orange-crowned Warbler in Colorado has surged: up 416% on the route-weighted index since 1973.

+416%Since 1973TrendPercent 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 →
68Routes 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 →
49YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Orange-crowned 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 →

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 →

Orange-crowned Warbler has surged in Colorado: up 416% on the route-weighted index since 1973.

Orange-crowned Warbler Population Forecast in Colorado

If the recent trend holds, Orange-crowned Warbler in Colorado is projected to stay roughly flat through 2029, near 1.3 (95% range 0.80–1.8). A 5-year backtest shows a typical error of ±39.3%, with 80% of held-out values landing inside the 95% band.

-5%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 →
1.3Projected 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 →
0.80–1.895% 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 →
±39.3%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, Orange-crowned Warbler in Colorado is projected to stay roughly flat through 2029, near 1.3 (95% range 0.80–1.8). A 5-year backtest shows a typical error of ±39.3%, with 80% 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 →
20251.20.731.7
20261.20.751.7
20271.30.761.7
20281.30.781.8
20291.30.801.8

Orange-crowned Warbler Survey Routes in Colorado

Routes recording Orange-crowned 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 →
Owl Creek Pass1520241998
Mcphee Res.1420241996
Baxter Pass1320241994
Haycamp Mesa1320241998
Aspen1220241985
Dolores Riv1020241988
Douglas Pass720241986
Blackhead Pk720211991
Yampa620231975
Groundhog Rs620241992
Nucla620241999
Black Sulphur Cr620242015
Yellowjacket Pass520242007
Delta420211973
Colona420121972
Uncompahgre420241988
Lake City 2420242017
Pagosa Spgs319821974
Lake City320021988
Fox Creek320242008
Angora320241998
Red Cliff220171992
Doyleville219881988
Ragged Mtn.220191994
Como220231999

Orange-crowned Warbler Population Trend in Other States

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