Species · Idaho · BBS 2025 Release · 1966–2024
Forster's Tern Population Trend in Idaho
Forster's Tern in Idaho has collapsed: down 89% on the route-weighted index since 1977.
-89%Since 1977
14Routes In State
27Years
Notable Forster's Tern Trends in Idaho
long arc declinecomputed index
Forster's Tern has collapsed in Idaho: down 89% on the route-weighted index since 1977.
Forster's Tern Population Forecast in Idaho
If the recent trend holds, Forster's Tern in Idaho is projected to stay roughly flat through 2020, near 0.00 (95% range 0.00–0.57). A 5-year backtest shows a typical error of ±464.4%, with 100% of held-out values landing inside the 95% band.
n/aChange by 2020
0.00Projected 2020 index
0.00–0.5795% range
±464.4%Backtest error
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2016 | 0.00 | 0.00 | 0.57 |
| 2017 | 0.00 | 0.00 | 0.57 |
| 2018 | 0.00 | 0.00 | 0.57 |
| 2019 | 0.00 | 0.00 | 0.57 |
| 2020 | 0.00 | 0.00 | 0.57 |
Forster's Tern Survey Routes in Idaho
| Glenns Ferry | 10 | 1968 | 1968 |
| Preston | 9 | 2004 | 1990 |
| Triangle | 5 | 2014 | 2003 |
| Cedar Hill | 4 | 2014 | 2002 |
| Pasadena Val | 2 | 2012 | 1987 |
| Picabo | 2 | 2015 | 2015 |
| Blackft Res | 1 | 2003 | 1985 |
| Tractor Flat | 1 | 2007 | 1990 |
| Centerville | 1 | 2011 | 2011 |
| Crane Creek | 1 | 1989 | 1989 |
| Springfield | 1 | 2007 | 1977 |
| Iron Springs | 1 | 1996 | 1996 |
| Featherville | 1 | 2010 | 1989 |
| Henry | 1 | 1979 | 1973 |
Forster's Tern Population Trend in Other States
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.