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Species · Colorado · BBS 2025 Release · 1966–2024

Virginia's Warbler Population Trend in Colorado

All statesForest birds

Virginia's Warbler in Colorado has surged: up 321% on the route-weighted index since 1973.

+321%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 →
65Routes 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 →
53YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Virginia'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 →

Virginia's Warbler has surged in Colorado: up 321% on the route-weighted index since 1973.

Virginia's Warbler Population Forecast in Colorado

If the recent trend holds, Virginia's Warbler in Colorado is projected to fall about 32% by 2029 — from 2.4 in 2024 to a central estimate of 1.6 (95% range 0.93–2.3). A 5-year backtest shows a typical error of ±48.5%, with 60% of held-out values landing inside the 95% band.

-32%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 →
1.6Projected 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 →
0.93–2.395% 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 →
±48.5%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, Virginia's Warbler in Colorado is projected to fall about 32% by 2029 — from 2.4 in 2024 to a central estimate of 1.6 (95% range 0.93–2.3). A 5-year backtest shows a typical error of ±48.5%, with 60% of held-out values landing inside the 95% band.19692029
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 →
20251.50.852.2
20261.60.872.2
20271.60.892.3
20281.60.912.3
20291.60.932.3

Virginia's Warbler Survey Routes in Colorado

Routes recording Virginia'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 →
Mesaverde Np4020241996
Baxter Pass3520241996
Douglas Pass2420241982
Yellowjacket Pass2120241998
Angora1920241998
Nucla1220241999
Buford1020241980
Wilson Creek1020241990
Ludlow920161998
Ragged Mtn.820191994
Gribbles Prk820241998
Delta720211973
Black Sulphur Cr720242015
Cheesman Lk620241969
Rosevale620232009
Cokedale620241995
Cortez 2520172009
Dolores Riv520241988
Marshall Pas520021998
Pagosa Spgs419751975
Wet Mtns.420241993
Gold Hill420121998
Haycamp Mesa420241998
Gold Hill 2320232023
Paonia320241992

Virginia's Warbler Population Trend in Other States

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