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

Gray Vireo Population Trend in Colorado

All statesForest birds

Gray Vireo in Colorado has surged: up 323% on the route-weighted index since 1976.

+323%Since 1976TrendPercent 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 →
25Routes 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 →
40YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Gray Vireo 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 Gray Vireo in Colorado. See the full index history below.

Gray Vireo Population Forecast in Colorado

If the recent trend holds, Gray Vireo in Colorado is projected to rise about 59% by 2030 — from 0.09 in 2025 to a central estimate of 0.15 (95% range 0.05–0.25). A 5-year backtest shows a typical error of ±34.6%, with 40% of held-out values landing inside the 95% band.

+59%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 →
0.15Projected 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 →
0.05–0.2595% 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 →
±34.6%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, Gray Vireo in Colorado is projected to rise about 59% by 2030 — from 0.09 in 2025 to a central estimate of 0.15 (95% range 0.05–0.25). A 5-year backtest shows a typical error of ±34.6%, with 40% of held-out values landing inside the 95% band.19742030
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 →
20260.140.040.24
20270.140.040.24
20280.140.040.24
20290.140.050.24
20300.150.050.25

Gray Vireo Survey Routes in Colorado

Routes recording Gray Vireo 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 →
Animas720041996
Rosevale320252013
Baxter Pass320241995
Blackhead Pk320002000
Maybell220232016
Mesaverde Np220252003
Douglas Pass220241988
Falfa219911991
Wray Gulch220192005
Animas 2220252005
Dinosaur220232001
Villegreen220242006
Basin220232014
Angora220252001
Radium219981998
Delta120161974
Wilson Creek120182018
Cortez 2120132013
Lay120172017
Trinchera120212021
De Beque120182009
Pinon120232023
Ninaview120102010
Nucla120252000
Gardner120002000

Gray Vireo Population Trend in Other States

arizonacalifornianevadanew-mexicotexasutah

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