Species · Maine · BBS 2025 Release · 1966–2024
Northern Harrier Population Trend in Maine
Northern Harrier in Maine has fallen sharply: down 56% on the route-weighted index since 1975.
-56%Since 1975
26Routes In State
36Years
Notable Northern Harrier Trends in Maine
long arc declinecomputed index
Northern Harrier has fallen sharply in Maine: down 56% on the route-weighted index since 1975.
Northern Harrier Population Forecast in Maine
If the recent trend holds, Northern Harrier in Maine is projected to fall about 74% by 2027 — from 0.10 in 2022 to a central estimate of 0.03 (95% range 0.00–0.11). A 5-year backtest shows a typical error of ±56%, with 100% of held-out values landing inside the 95% band.
-74%Change by 2027
0.03Projected 2027 index
0.00–0.1195% range
±56%Backtest error
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2023 | 0.03 | 0.00 | 0.12 |
| 2024 | 0.03 | 0.00 | 0.12 |
| 2025 | 0.03 | 0.00 | 0.11 |
| 2026 | 0.03 | 0.00 | 0.11 |
| 2027 | 0.03 | 0.00 | 0.11 |
Northern Harrier Survey Routes in Maine
| Hancock | 2 | 1987 | 1986 |
| Ft Fairfield | 2 | 2004 | 1994 |
| Westbrook | 1 | 1986 | 1986 |
| South Arm | 1 | 1995 | 1995 |
| Otisfield Gr | 1 | 1999 | 1995 |
| Manchester | 1 | 1982 | 1981 |
| Harmony | 1 | 2022 | 1991 |
| Heron Lake | 1 | 1989 | 1989 |
| Brooks | 1 | 2006 | 2006 |
| Eastbrook | 1 | 2017 | 2017 |
| Cooper | 1 | 1978 | 1975 |
| Deblois | 1 | 2005 | 1966 |
| Moose River | 1 | 2006 | 2006 |
| Wytopitlock | 1 | 1983 | 1983 |
| Forest Sta | 1 | 1983 | 1979 |
| Ludlow | 1 | 1981 | 1978 |
| Washburn | 1 | 1987 | 1983 |
| Horse Mtn | 1 | 1995 | 1995 |
| Ashland | 1 | 2004 | 1988 |
| Boundary | 1 | 2015 | 1995 |
| St David | 1 | 2005 | 1984 |
| Lake Moxie | 1 | 2010 | 2010 |
| Cornville | 1 | 2022 | 2022 |
| Searsport | 1 | 2007 | 2007 |
| Jefferson | 1 | 2008 | 2008 |
Northern Harrier Population Trend in Other States
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Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.