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

Common Grackle Population Trend in Montana

All statesGeneralists

Common Grackle in Montana has surged: up 231% on the route-weighted index since 1970.

+231%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 →
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 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 231% 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 50% by 2030 — from 7.2 in 2025 to a central estimate of 3.6 (95% range 0.76–6.4). A 5-year backtest shows a typical error of ±45.3%, with 60% of held-out values landing inside the 95% band.

-50%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 →
3.6Projected 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 →
0.76–6.495% 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 →
±45.3%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 50% by 2030 — from 7.2 in 2025 to a central estimate of 3.6 (95% range 0.76–6.4). A 5-year backtest shows a typical error of ±45.3%, with 60% 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 →
20263.50.686.4
20273.50.706.4
20283.60.726.4
20293.60.746.4
20303.60.766.4

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 →
Cabin Creek7520252018
Redstone6020251975
Lambert5220252021
Harlem4520211968
Glentana4220252015
Westby3620252015
Glasgow3520251968
Brandenberg3320251969
Albion2520251982
Church Hill2520252017
Miles City2320252015
Webster2020251979
Reed Point1720251977
St Xavier1620111979
Winifred1620232023
Custer 21620252024
Sun River1520192016
Clyde Park1520252018
Coleman Coulee1320242017
Lindsay1220242015
Chuffey Spring1220252016
Chinook1120252015
Saco1120252015
Wolf Point1120242015
Custer1120222019

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 2026-08-14.