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

Great-tailed Grackle Population Trend in Colorado

All statesWetland birds

Great-tailed Grackle in Colorado has surged: up 239% on the route-weighted index since 1984.

+239%Since 1984TrendPercent 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 →
43Routes 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 →
40YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Great-tailed 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 →

Great-tailed Grackle has surged in Colorado: up 239% on the route-weighted index since 1984.

Great-tailed Grackle Population Forecast in Colorado

If the recent trend holds, Great-tailed Grackle in Colorado is projected to rise about 35% by 2030 — from 0.52 in 2025 to a central estimate of 0.70 (95% range 0.28–1.1). A 5-year backtest shows a typical error of ±53.7%, with 100% of held-out values landing inside the 95% band.

+35%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 →
0.70Projected 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 →
0.28–1.195% 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 →
±53.7%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, Great-tailed Grackle in Colorado is projected to rise about 35% by 2030 — from 0.52 in 2025 to a central estimate of 0.70 (95% range 0.28–1.1). A 5-year backtest shows a typical error of ±53.7%, with 100% of held-out values landing inside the 95% band.19822030
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 →
20260.650.231.1
20270.660.241.1
20280.680.251.1
20290.690.261.1
20300.700.281.1

Great-tailed Grackle Survey Routes in Colorado

Routes recording Great-tailed 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 →
Bethune3120182001
Doyle Bridge 21720221998
Edler1520252003
Doyle Bridge1219971996
Cheyenne1120251998
Prospect Valley 2920102001
Flagler920251997
Pritchett720192007
Lamar620231995
Two Buttes520251985
Limon520222015
Dolores419871982
Gilpin420252017
Cone Mtn420072007
Fleming320232005
Rush320242024
Fort Morgan320252000
Burlington320242008
Hudson220212000
Cortez 2220142013
Nunn220212016
Julesburg220211998
Alamosa220251997
Campo220252000
Ellicott220232013

Great-tailed Grackle Population Trend in Other States

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