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

Brown-headed Cowbird Population Trend in Idaho

All statesGeneralists

Brown-headed Cowbird in Idaho has edged down: down 24% on the route-weighted index since 1970.

-24%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 →
64Routes 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 Brown-headed Cowbird Trends in IdahoNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Brown-headed Cowbird in Idaho. See the full index history below.

Brown-headed Cowbird Population Forecast in Idaho

If the recent trend holds, Brown-headed Cowbird in Idaho is projected to rise about 76% by 2029 — from 3.2 in 2024 to a central estimate of 5.6 (95% range 0.00–11). A 5-year backtest shows a typical error of ±60.1%, with 100% of held-out values landing inside the 95% band.

+76%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 →
5.6Projected 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 →
0.00–1195% 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 →
±60.1%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, Brown-headed Cowbird in Idaho is projected to rise about 76% by 2029 — from 3.2 in 2024 to a central estimate of 5.6 (95% range 0.00–11). A 5-year backtest shows a typical error of ±60.1%, 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 →
20255.80.0112
20265.70.0012
20275.70.0011
20285.70.0011
20295.60.0011

Brown-headed Cowbird Survey Routes in Idaho

Routes recording Brown-headed Cowbird in Idaho.
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 →
Cascade5519841968
Glenns Ferry2719861968
Picabo2020211988
Pocatello1820191979
Cedar Hill1820241989
Cabarton1820231985
Joel1720241989
Gifford1420171971
Mud Lake920231988
Pierce820071990
Ririe720231971
Cape Horn620241972
Acequia620121979
Almo620231988
Daniels Res620191988
Baker520241976
Coolin520241986
Triangle420241985
Henry419831973
Sawtooth City 2420242015
Salmon River419941994
Naples320241973
Mivoden320231977
Leadore320231984
Dubois320241972

Brown-headed Cowbird Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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