BirdAnalyst
Species · Colorado · BBS 2025 Release · 1966–2024

Gray Flycatcher Population Trend in Colorado

All statesAerial insectivores

Gray Flycatcher in Colorado has surged: up 435% on the route-weighted index since 1975.

+435%Since 1975TrendPercent 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 →
36Routes 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 →
47YearsYears 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 Flycatcher 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 →

Gray Flycatcher has surged in Colorado: up 435% on the route-weighted index since 1975.

Gray Flycatcher Population Forecast in Colorado

If the recent trend holds, Gray Flycatcher in Colorado is projected to rise about 26% by 2029 — from 0.54 in 2024 to a central estimate of 0.68 (95% range 0.42–0.93). A 5-year backtest shows a typical error of ±46.6%, with 100% of held-out values landing inside the 95% band.

+26%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 →
0.68Projected 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 →
0.42–0.9395% 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 →
±46.6%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 Flycatcher in Colorado is projected to rise about 26% by 2029 — from 0.54 in 2024 to a central estimate of 0.68 (95% range 0.42–0.93). A 5-year backtest shows a typical error of ±46.6%, with 100% of held-out values landing inside the 95% band.19732029
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 →
20250.630.380.88
20260.640.390.90
20270.650.400.91
20280.660.410.92
20290.680.420.93

Gray Flycatcher Survey Routes in Colorado

Routes recording Gray Flycatcher 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 →
Wray Gulch1120231988
Walsenburg1020242003
Animas 2820182005
Piceance Basin820041998
Maybell720241973
Delta720211974
Angora720241998
Animas520041996
Cokedale520242021
Baxter Pass420241995
Basin420241995
Great Divide320121998
Douglas Pass320241986
Browns Park320241993
Mesaverde Np220241996
Dinosaur220241995
Rifle Falls220211998
Nucla220242001
Owl Creek Pass220132005
Ludlow220092008
Buford120012001
Falfa120172003
Summitville120132013
Wilson Creek120192002
Lay120242014

Gray Flycatcher Population Trend in Other States

arizonacaliforniaidahonevadanew-mexicooregontexasutahwashingtonwyoming

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