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Species · Colorado · BBS 2025 Release · 1966–2024

Blue-gray Gnatcatcher Population Trend in Colorado

All statesForest birds

Blue-gray Gnatcatcher in Colorado has surged: up 647% on the route-weighted index since 1973.

+647%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 →
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 Blue-gray Gnatcatcher 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 →

Blue-gray Gnatcatcher has surged in Colorado: up 647% on the route-weighted index since 1973.

Blue-gray Gnatcatcher Population Forecast in Colorado

If the recent trend holds, Blue-gray Gnatcatcher in Colorado is projected to rise about 10% by 2029 — from 2.0 in 2024 to a central estimate of 2.2 (95% range 1.6–2.8). A 5-year backtest shows a typical error of ±29.6%, with 80% of held-out values landing inside the 95% band.

+10%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 →
2.2Projected 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 →
1.6–2.895% 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 →
±29.6%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, Blue-gray Gnatcatcher in Colorado is projected to rise about 10% by 2029 — from 2.0 in 2024 to a central estimate of 2.2 (95% range 1.6–2.8). A 5-year backtest shows a typical error of ±29.6%, with 80% 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 →
20252.01.42.7
20262.11.52.7
20272.11.52.7
20282.11.52.8
20292.21.62.8

Blue-gray Gnatcatcher Survey Routes in Colorado

Routes recording Blue-gray Gnatcatcher 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 Np3420241996
Wray Gulch3420231988
Douglas Pass2920241982
Baxter Pass2720241994
Angora1620241998
De Beque1420241992
Black Sulphur Cr1320242015
Rosevale1220242009
Animas1120001996
Dinosaur920241995
Wet Mtns.720241993
Nucla720242000
Delta620211973
Basin620241995
Ludlow620162006
Cortez 2520172009
Dolores Riv519971997
Maybell420241974
Guffey419971997
Westcliffe420151999
Cortez420081988
Great Divide320191980
Yampa320091975
Pagosa Spgs319821982
Pinon320241995

Blue-gray Gnatcatcher Population Trend in Other States

alabamaarizonaarkansascaliforniaconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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