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

Common Grackle Population Trend in Montana

All statesGeneralists

Common Grackle in Montana has surged: up 178% on the route-weighted index since 1970.

+178%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 →
75Routes 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 MontanaNotable 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 Montana: up 178% on the route-weighted index since 1970.

Common Grackle Population Forecast in Montana

If the recent trend holds, Common Grackle in Montana is projected to fall about 48% by 2029 — from 6.2 in 2024 to a central estimate of 3.3 (95% range 0.59–6.0). A 5-year backtest shows a typical error of ±38.3%, with 80% of held-out values landing inside the 95% band.

-48%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 →
3.3Projected 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 →
0.59–6.095% 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 →
±38.3%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 Montana is projected to fall about 48% by 2029 — from 6.2 in 2024 to a central estimate of 3.3 (95% range 0.59–6.0). A 5-year backtest shows a typical error of ±38.3%, with 80% 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 →
20253.20.555.9
20263.20.565.9
20273.30.575.9
20283.30.585.9
20293.30.596.0

Common Grackle Survey Routes in Montana

Routes recording Common Grackle in Montana.
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 →
Westby7620242015
Glasgow5620241968
Harlem4520211968
Glentana3920242015
Lambert3220242021
Custer 22820242024
Webster2620241979
Miles City2620242015
Redstone2020241975
Chinook2020242015
Church Hill2020242017
St Xavier1620111979
Winifred1620232023
Sun River1520192016
Lindsay1220242015
Saco1120242015
Wolf Point1120242015
Custer1120222019
Great Falls1020241972
Reed Point1020241977
Albion1020241982
St Mary919711971
Cleveland920241985
Powderville920241970
Gildford920242018

Common Grackle Population Trend in Other States

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

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