Species · Wisconsin · BBS 2025 Release · 1966–2024
Forster's Tern Population Trend in Wisconsin
Forster's Tern in Wisconsin has edged down: down 24% on the route-weighted index since 1974.
-24%Since 1974
12Routes In State
48Years
Notable Forster's Tern Trends in Wisconsin
No notable trend signals for Forster's Tern in Wisconsin. See the full index history below.
Forster's Tern Population Forecast in Wisconsin
If the recent trend holds, Forster's Tern in Wisconsin is projected to stay roughly flat through 2029, near 0.01 (95% range 0.00–0.22). A 5-year backtest shows a typical error of ±170.4%, with 100% of held-out values landing inside the 95% band.
n/aChange by 2029
0.01Projected 2029 index
0.00–0.2295% range
±170.4%Backtest error
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.03 | 0.00 | 0.23 |
| 2026 | 0.02 | 0.00 | 0.23 |
| 2027 | 0.02 | 0.00 | 0.23 |
| 2028 | 0.02 | 0.00 | 0.22 |
| 2029 | 0.01 | 0.00 | 0.22 |
Forster's Tern Survey Routes in Wisconsin
| Casco | 4 | 1989 | 1989 |
| Omro | 3 | 2001 | 1972 |
| Rolling Pr | 3 | 2010 | 1995 |
| Washington I | 3 | 1974 | 1974 |
| Hudson | 2 | 1986 | 1986 |
| Rib Lake | 2 | 2008 | 2008 |
| Briggsville | 2 | 2005 | 2005 |
| Bayfield | 1 | 2008 | 2008 |
| Manawa | 1 | 2001 | 2001 |
| Omro 2 | 1 | 2022 | 2002 |
| Pardeeville | 1 | 2024 | 1992 |
| Brownsville | 1 | 2008 | 1975 |
Forster's Tern Population Trend in Other States
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.