Species · Delaware · BBS 2025 Release · 1966–2024
Forster's Tern Population Trend in Delaware
Forster's Tern in Delaware has surged: up 37× on the route-weighted index since 1977.
37×Since 1977
9Routes In State
37Years
Notable Forster's Tern Trends in Delaware
long arc increasecomputed index
Forster's Tern has surged in Delaware: up 37× on the route-weighted index since 1977.
Forster's Tern Population Forecast in Delaware
If the recent trend holds, Forster's Tern in Delaware is projected to rise about 201% by 2029 — from 1.2 in 2024 to a central estimate of 3.6 (95% range 0.00–7.9). A 5-year backtest shows a typical error of ±111%, with 60% of held-out values landing inside the 95% band.
+201%Change by 2029
3.6Projected 2029 index
0.00–7.995% range
±111%Backtest error
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 3.3 | 0.00 | 7.6 |
| 2026 | 3.4 | 0.00 | 7.7 |
| 2027 | 3.5 | 0.00 | 7.7 |
| 2028 | 3.5 | 0.00 | 7.8 |
| 2029 | 3.6 | 0.00 | 7.9 |
Forster's Tern Survey Routes in Delaware
| Pepperbox 2 | 5 | 2024 | 2017 |
| Bethany Bch | 4 | 1989 | 1985 |
| Pepperbox | 4 | 2016 | 1998 |
| Lowes Xrds | 2 | 1991 | 1974 |
| Harrington | 1 | 2023 | 1992 |
| Dover | 1 | 1966 | 1966 |
| Frankford | 1 | 2006 | 2006 |
| Blackbird | 1 | 2024 | 1994 |
| Georgetown | 1 | 2006 | 1992 |
Forster's Tern Population Trend in Other States
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.