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

Common Grackle Population Trend in Colorado

All statesGeneralists

Common Grackle in Colorado has surged: up 193% on the route-weighted index since 1970.

+193%Since 1970TrendPercent 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 →
116Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Common Grackle 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 →

Common Grackle has surged in Colorado: up 192% on the route-weighted index since 1970.

Common Grackle Population Forecast in Colorado

If the recent trend holds, Common Grackle in Colorado is projected to rise about 98% by 2030 — from 6.6 in 2025 to a central estimate of 13 (95% range 0.00–29). A 5-year backtest shows a typical error of ±108.1%, with 100% of held-out values landing inside the 95% band.

+98%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 →
13Projected 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 →
0.00–2995% 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 →
±108.1%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, Common Grackle in Colorado is projected to rise about 98% by 2030 — from 6.6 in 2025 to a central estimate of 13 (95% range 0.00–29). A 5-year backtest shows a typical error of ±108.1%, with 100% of held-out values landing inside the 95% band.19682030
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 →
2026130.0028
2027130.0028
2028130.0029
2029130.0029
2030130.0029

Common Grackle Survey Routes in Colorado

Routes recording Common Grackle 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 →
Julesburg13620211998
Hudson12420251988
Fleming7920251968
Nunn7520251995
Bennett7220251995
Prospect Val6520001992
Waverly5820191988
Fort Morgan4920251996
Amherst4320241992
Flagler4120251997
Wildhorse L3520251989
Kirk3320231992
Abarr2720231974
Adams Co.2720221989
Limon2420251992
Doyle Bridge2419971992
Grover2320241992
Harmony2120251973
Timpas1820251995
Arsenal1820151991
Prospect Valley 21820252001
Parlin1620181978
Gordon Creek1620251988
Cheyenne1520251990
Sheridan Lak1420161995

Common Grackle Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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