BirdAnalyst
Species · BCR 30 · BBS 2025 Release · 1966–2024

Brown-headed Cowbird In New England / Mid-Atlantic Coast

All regionsNew England / Mid-Atlantic CoastGeneralists

Brown-headed Cowbird in New England / Mid-Atlantic Coast has risen sharply: up 54% on the route-weighted index since 1968.

+54%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 →
164Routes 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 →

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 →

Brown-headed Cowbird has risen sharply in New England / Mid-Atlantic Coast: up 54% on the route-weighted index since 1968.

Brown-headed Cowbird In New England / Mid-Atlantic Coast Population Forecast

If the recent trend holds, Brown-headed Cowbird in New England / Mid-Atlantic Coast is projected to stay roughly flat through 2029, near 11 (95% range 8.7–13). A 5-year backtest shows a typical error of ±11%, with 80% of held-out values landing inside the 95% band.

+8%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 →
11Projected 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 →
8.7–1395% 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 →
±11%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 New England / Mid-Atlantic Coast is projected to stay roughly flat through 2029, near 11 (95% range 8.7–13). A 5-year backtest shows a typical error of ±11%, with 80% 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 →
2025108.412
2026108.512
2027118.612
2028118.613
2029118.713

Routes In New England / Mid-Atlantic Coast

Routes recording Brown-headed Cowbird in New England / Mid-Atlantic Coast.
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 →
Jones BeachNEW-YORK442013
WillimanticCONNECTICUT342018
MadisonMARYLAND342024
CokesburyMARYLAND342024
MysticCONNECTICUT302023
Chincoteag WVIRGINIA292022
HolleyvilleDELAWARE272004
Island CreekMARYLAND272024
Block IslandRHODE-ISLAND272010
La PlataMARYLAND242009
Forest GroveMARYLAND242023
HarringtonDELAWARE232024
HolmansvilleNEW-JERSEY222009
Spraguetown 2NEW-JERSEY212007
BlackbirdDELAWARE202024
DavidsnvilleMARYLAND202024
PomonaNEW-JERSEY202024
MarionMASSACHUSETTS192024
BrandonVIRGINIA192024
Holleyville 2DELAWARE182024
Milton 2DELAWARE182017
Tall TimbersMARYLAND182014
SinepuxentMARYLAND181978
FrankfordDELAWARE172012
MillingtonMARYLAND172024

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