BirdAnalyst
Species · Delaware · BBS 2025 Release · 1966–2024

Northern Harrier Population Trend in Delaware

All statesGeneralists

Northern Harrier in Delaware has increased: up 26% on the route-weighted index since 1979.

+26%Since 1979
6Routes In State
22Years

Notable Northern Harrier Trends in Delaware

No notable trend signals for Northern Harrier in Delaware. See the full index history below.

Northern Harrier Population Forecast in Delaware

If the recent trend holds, Northern Harrier in Delaware is projected to fall about 20% by 2029 — from 0.20 in 2024 to a central estimate of 0.16 (95% range 0.00–0.35). A 5-year backtest shows a typical error of ±16.7%, with 100% of held-out values landing inside the 95% band.

-20%Change by 2029
0.16Projected 2029 index
0.00–0.3595% range
±16.7%Backtest error
19722029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected index95% low95% high
20250.160.000.35
20260.160.000.35
20270.160.000.35
20280.160.000.35
20290.160.000.35

Northern Harrier Survey Routes in Delaware

Routes recording Northern Harrier in Delaware.
Dover219791979
Mt Pleasant119961996
Wilmington119961996
Harrington120241972
Blackbird120111995
Georgetown119921992

Northern Harrier Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradogeorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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