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Species · Colorado · BBS 2026 Release · 1966–2025

Grace's Warbler Population Trend in Colorado

All statesForest birds

Grace's Warbler in Colorado has surged: up 185% on the route-weighted index since 1980.

+185%Since 1980TrendPercent 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 →
19Routes 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 →
34YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Grace's 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 →

Grace's Warbler has surged in Colorado: up 185% on the route-weighted index since 1980.

Grace's Warbler Population Forecast in Colorado

If the recent trend holds, Grace's Warbler in Colorado is projected to fall about 26% by 2030 — from 0.46 in 2025 to a central estimate of 0.34 (95% range 0.17–0.51). A 5-year backtest shows a typical error of ±29.5%, with 60% of held-out values landing inside the 95% band.

-26%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 →
0.34Projected 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 →
0.17–0.5195% 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 →
±29.5%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, Grace's Warbler in Colorado is projected to fall about 26% by 2030 — from 0.46 in 2025 to a central estimate of 0.34 (95% range 0.17–0.51). A 5-year backtest shows a typical error of ±29.5%, with 60% of held-out values landing inside the 95% band.19692030
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 →
20260.330.160.49
20270.330.160.50
20280.330.170.50
20290.340.170.51
20300.340.170.51

Grace's Warbler Survey Routes in Colorado

Routes recording Grace's 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 →
Mcphee Res.2820251997
Haycamp Mesa1120251998
Pagosa Spgs519751975
Cortez 2420152010
Nucla420252000
Delta220212011
Dolores219691969
Uncompahgre220251999
Walsenburg220032003
Cortez220061997
Blackhead Pk220251998
Colona119801980
Powderhorn120232008
Animas119961996
Pinon120232013
Piedra120251992
Cokedale120252019
Colona 2120252025
Ludlow120142009

Grace's Warbler Population Trend in Other States

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Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.