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

Northern Harrier In New England / Mid-Atlantic Coast

All regionsNew England / Mid-Atlantic CoastGeneralists

Northern Harrier in New England / Mid-Atlantic Coast has fallen sharply: down 66% on the route-weighted index since 1972.

-66%Since 1972TrendPercent 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 →
35Routes 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 →
46YearsYears 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 Northern Harrier in New England / Mid-Atlantic Coast. See the full index history below.

Forecast

If the recent trend holds, Northern Harrier in New England / Mid-Atlantic Coast is projected to stay roughly flat through 2029, near 0.05 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±338.2%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.05Projected 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 →
0.00–0.1395% 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 →
±338.2%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, Northern Harrier in New England / Mid-Atlantic Coast is projected to stay roughly flat through 2029, near 0.05 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±338.2%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.050.000.13
20260.050.000.13
20270.050.000.13
20280.050.000.13
20290.050.000.13

Routes In New England / Mid-Atlantic Coast

Routes recording Northern Harrier 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 →
DoverDELAWARE21979
ChilmarkMASSACHUSETTS21971
Six PointsNEW-JERSEY22014
RooseveltNEW-JERSEY21997
Block IslandRHODE-ISLAND22010
Mt PleasantDELAWARE11996
WilmingtonDELAWARE11996
HarringtonDELAWARE12024
BlackbirdDELAWARE12011
GeorgetownDELAWARE11992
Broomes IslMARYLAND11989
ElktonMARYLAND11993
MillingtonMARYLAND11996
MelitotaMARYLAND12016
Piney NeckMARYLAND11982
MatthewsMARYLAND12003
EastonMARYLAND11996
Golden HillMARYLAND11991
HongaMARYLAND12000
MadisonMARYLAND12017
CokesburyMARYLAND12009
NewarkMARYLAND11996
Grove NeckMARYLAND11996
PrattvilleMASSACHUSETTS11973
NewburyportMASSACHUSETTS11976

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