Species · Oregon · BBS 2025 Release · 1966–2024
Black Tern Population Trend in Oregon
Black Tern in Oregon has collapsed: down 95% on the route-weighted index since 1972.
-95%Since 1972
17Routes In State
51Years
Notable Black Tern Trends in Oregon
long arc declinecomputed index
Black Tern has collapsed in Oregon: down 95% on the route-weighted index since 1972.
Black Tern Population Forecast in Oregon
If the recent trend holds, Black Tern in Oregon is projected to fall about 100% by 2029 — from 0.18 in 2024 to a central estimate of 0.00 (95% range 0.00–0.97). A 5-year backtest shows a typical error of ±120.5%, with 100% of held-out values landing inside the 95% band.
-100%Change by 2029
0.00Projected 2029 index
0.00–0.9795% range
±120.5%Backtest error
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.03 | 0.00 | 1.00 |
| 2026 | 0.01 | 0.00 | 0.98 |
| 2027 | 0.00 | 0.00 | 0.97 |
| 2028 | 0.00 | 0.00 | 0.97 |
| 2029 | 0.00 | 0.00 | 0.97 |
Black Tern Survey Routes in Oregon
| Warner Vally | 35 | 2007 | 2003 |
| Catlow Rim | 20 | 2016 | 2013 |
| Fish Lake | 17 | 2024 | 1972 |
| Blizzard Gap | 12 | 2005 | 1987 |
| Bly | 10 | 2001 | 1992 |
| Chinchalo | 7 | 2021 | 1993 |
| Barnes Val | 5 | 1987 | 1974 |
| Adair | 4 | 2001 | 2001 |
| Harney Lake | 4 | 2003 | 1996 |
| Dell Spring | 2 | 1976 | 1976 |
| Modoc Point | 2 | 2002 | 1969 |
| Merrill | 1 | 2005 | 2005 |
| Lapham Res. | 1 | 2007 | 1991 |
| Mount Vernon | 1 | 2009 | 1987 |
| Princeton | 1 | 1985 | 1972 |
| Lakeview | 1 | 2005 | 1999 |
| Malheur Nwr | 1 | 1998 | 1986 |
Black Tern Population Trend in Other States
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.