BirdAnalyst
Species · BCR 14 · BBS 2025 Release · 1966–2024

Brown-headed Cowbird In Atlantic Northern Forest

All regionsAtlantic Northern ForestGeneralists

Brown-headed Cowbird in Atlantic Northern Forest has collapsed: down 80% on the route-weighted index since 1968.

-80%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 →
144Routes 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 declinecomputed 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 collapsed in Atlantic Northern Forest: down 80% on the route-weighted index since 1968.

Brown-headed Cowbird In Atlantic Northern Forest Population Forecast

If the recent trend holds, Brown-headed Cowbird in Atlantic Northern Forest is projected to fall about 100% by 2029 — from 1.6 in 2024 to a central estimate of 0.00 (95% range 0.00–2.1). A 5-year backtest shows a typical error of ±86.4%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–2.195% 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 →
±86.4%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 Atlantic Northern Forest is projected to fall about 100% by 2029 — from 1.6 in 2024 to a central estimate of 0.00 (95% range 0.00–2.1). A 5-year backtest shows a typical error of ±86.4%, 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 →
20250.100.002.2
20260.000.002.1
20270.000.002.1
20280.000.002.1
20290.000.002.1

Routes In Atlantic Northern Forest

Routes recording Brown-headed Cowbird in Atlantic Northern Forest.
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 →
BentonMAINE221980
WatervilleVERMONT151980
N OrangeMASSACHUSETTS142024
WarrenMAINE101990
ManchesterMAINE91995
PetersburgNEW-YORK92013
Otisfield GrMAINE82015
PittsfieldMASSACHUSETTS82016
ConcordNEW-HAMPSHIRE82024
Hope FallsNEW-YORK81995
MarlboroVERMONT82024
TopsfieldMAINE71996
SheffieldMASSACHUSETTS72022
Old ForgeNEW-YORK71995
FletcherVERMONT72024
CheshireMASSACHUSETTS61994
Gilmantn I WNEW-HAMPSHIRE62024
TurnerMAINE52010
NorthfieldMAINE51981
Turner 2MAINE52024
NewcombNEW-YORK51993
Dexter LakeNEW-YORK51975
New HartfordCONNECTICUT41987
FreedomMAINE42021
HarmonyMAINE42024

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