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

Common Grackle Population Trend in Colorado

All statesGeneralists

Common Grackle in Colorado has surged: up 176% on the route-weighted index since 1970.

+176%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 →
113Routes 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 →
56YearsYears 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 176% 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 105% by 2029 — from 6.5 in 2024 to a central estimate of 13 (95% range 0.00–29). A 5-year backtest shows a typical error of ±92.2%, with 100% of held-out values landing inside the 95% band.

+105%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 →
13Projected 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 →
0.00–2995% 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 →
±92.2%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 105% by 2029 — from 6.5 in 2024 to a central estimate of 13 (95% range 0.00–29). A 5-year backtest shows a typical error of ±92.2%, with 100% of held-out values landing inside the 95% band.19682029
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 →
2025130.0029
2026130.0029
2027130.0029
2028130.0029
2029130.0029

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 →
Hudson15420241988
Julesburg13620211998
Bennett9120181995
Fort Morgan8420241996
Prospect Val6520001992
Waverly5820191988
Nunn5220211995
Amherst4320241992
Flagler4220241997
Prospect Valley 24220232001
Stoneham3620211992
Kirk3320231992
Cheyenne3020241990
Abarr2720231974
Adams Co.2720221989
Timpas2720191995
Briggsdale2420241968
Fleming2420241968
Doyle Bridge2419971992
Harmony2320241973
Wildhorse L2320241989
Grover2320241992
Limon2020241992
Arsenal1820151991
Arsenal 21820242016

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 2026-05-22.