BirdAnalyst
Species · BCR 13 · BBS 2025 Release · 1966–2024

Brown-headed Cowbird In Lower Great Lakes / St. Lawrence Plain

All regionsLower Great Lakes / St. Lawrence PlainGeneralists

Brown-headed Cowbird in Lower Great Lakes / St. Lawrence Plain has declined: down 37% on the route-weighted index since 1968.

-37%Since 1968TrendPercent 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 →
86Routes 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 →
58YearsYears 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 Lower Great Lakes / St. Lawrence Plain. See the full index history below.

Brown-headed Cowbird In Lower Great Lakes / St. Lawrence Plain Population Forecast

If the recent trend holds, Brown-headed Cowbird in Lower Great Lakes / St. Lawrence Plain is projected to fall about 13% by 2029 — from 8.3 in 2024 to a central estimate of 7.2 (95% range 4.5–9.9). A 5-year backtest shows a typical error of ±15.6%, with 100% of held-out values landing inside the 95% band.

-13%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 →
7.2Projected 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 →
4.5–9.995% 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 →
±15.6%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 Lower Great Lakes / St. Lawrence Plain is projected to fall about 13% by 2029 — from 8.3 in 2024 to a central estimate of 7.2 (95% range 4.5–9.9). A 5-year backtest shows a typical error of ±15.6%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20257.64.910
20267.54.810
20277.44.710
20287.34.610
20297.24.59.9

Routes In Lower Great Lakes / St. Lawrence Plain

Routes recording Brown-headed Cowbird in Lower Great Lakes / St. Lawrence Plain.
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 →
ChurchvilleNEW-YORK442024
Cicero CtrNEW-YORK382024
CayugaNEW-YORK332024
Ballston LkNEW-YORK251995
West BangorNEW-YORK201998
Valley CityOHIO202024
PenfieldNEW-YORK192024
MacdougallNEW-YORK172024
NashvilleNEW-YORK162018
West SenecaNEW-YORK152004
MaysvilleOHIO152012
New SomersetOHIO151993
Sugar GrovePENNSYLVANIA152023
HarmonsburgPENNSYLVANIA142023
PittsfieldOHIO132024
RomulusNEW-YORK122000
CastileNEW-YORK122024
N VictoryNEW-YORK121972
LucerneOHIO122024
CatskillsNEW-YORK112015
HamburgNEW-YORK112024
E YoungstownNEW-YORK112023
NaplesNEW-YORK112024
GarrettsvileOHIO111991
LenoxOHIO112024

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