BirdAnalyst
Species · BCR 9 · BBS 2026 Release · 1966–2025

Brown-headed Cowbird In Great Basin

All regionsGreat BasinGeneralists

Brown-headed Cowbird in Great Basin has increased: up 30% on the route-weighted index since 1970.

+30%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 →
256Routes In RegionSurvey 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 SignalsNotable 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 Great Basin. See the full index history below.

Brown-headed Cowbird In Great Basin Population Forecast

If the recent trend holds, Brown-headed Cowbird in Great Basin is projected to stay roughly flat through 2030, near 7.8 (95% range 2.8–13). A 5-year backtest shows a typical error of ±55.3%, with 100% of held-out values landing inside the 95% band.

+6%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 →
7.8Projected 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 →
2.8–1395% 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 →
±55.3%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, Brown-headed Cowbird in Great Basin is projected to stay roughly flat through 2030, near 7.8 (95% range 2.8–13). A 5-year backtest shows a typical error of ±55.3%, with 100% 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 →
20267.92.913
20277.92.913
20287.92.913
20297.82.913
20307.82.813

Routes In Great Basin

Routes recording Brown-headed Cowbird in Great Basin.
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 →
DorrisCALIFORNIA2002019
CedarvilleCALIFORNIA602025
OthelloWASHINGTON521991
TwispWASHINGTON492024
Gardnerville 2NEVADA482025
Scootney ReservoirWASHINGTON402025
Modoc Point 2OREGON392025
LikelyCALIFORNIA312025
Columbia NwrWASHINGTON292022
Iron GateCALIFORNIA282019
PicaboIDAHO282025
Glenns FerryIDAHO271986
MesaWASHINGTON272008
SnowdenWASHINGTON262025
LeavenworthWASHINGTON252024
RirieIDAHO242025
Ruby ValleyNEVADA242001
GoshenUTAH242025
ArdenvoirWASHINGTON231987
Lake ChelanWASHINGTON232025
HarringtonWASHINGTON222012
Crowder FlatCALIFORNIA212019
Mud LakeIDAHO212025
Daniels ResIDAHO212025
ChinchaloOREGON202025

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