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

Evening Grosbeak Population Trend in Colorado

All statesGeneralists

Evening Grosbeak in Colorado has increased: up 43% on the route-weighted index since 1975.

+43%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 →
56Routes 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 Evening Grosbeak 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 Evening Grosbeak in Colorado. See the full index history below.

Evening Grosbeak Population Forecast in Colorado

If the recent trend holds, Evening Grosbeak in Colorado is projected to stay roughly flat through 2029, near 0.29 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±34.6%, with 100% of held-out values landing inside the 95% band.

+2%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 →
0.29Projected 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 →
0.00–1.495% 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, Evening Grosbeak in Colorado is projected to stay roughly flat through 2029, near 0.29 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±34.6%, with 100% 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 →
20250.310.001.4
20260.310.001.4
20270.300.001.4
20280.300.001.4
20290.290.001.4

Evening Grosbeak Survey Routes in Colorado

Routes recording Evening Grosbeak 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 →
Owl Creek Pass1120242008
Summitville1020151993
Powderhorn820232016
Flattops820172017
Groundhog Rs820192006
Rifle Falls720031998
Elbert620242011
Wet Mtns.519941994
Parlin419881988
Tarryall420231988
Dolores Riv420211988
Pinos Creek419891988
Marshall Pas420111995
Cokedale420232018
Gardner420082008
Mount Evans320242024
Colona320101975
Castleton320241994
Steamboat L.320061996
Guffey320241991
Ragged Mtn.320181999
Gribbles Prk320232010
Dunckley Pas320231994
Pinon320071993
Paonia320192019

Evening Grosbeak Population Trend in Other States

arizonacaliforniaconnecticutidahomainemassachusettsmichiganminnesotamontananevadanew-hampshirenew-mexiconew-yorkoregonsouth-dakotautahvermontwashingtonwisconsinwyoming

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