Species · BCR 4 · BBS 2025 Release · 1966–2024
Tree Swallow In BCR 4
Tree Swallow in BCR 4 has collapsed: down 83% on the route-weighted index since 1976.
-83%Since 1976
59Routes In Region
47Years
Notable Signals
long arc declinecomputed index
Tree Swallow has collapsed in BCR 4: down 83% on the route-weighted index since 1976.
Forecast
If the recent trend holds, Tree Swallow in BCR 4 is projected to fall about 100% by 2029 — from 1.3 in 2024 to a central estimate of 0.00 (95% range 0.00–5.4). A 5-year backtest shows a typical error of ±119.8%, with 100% of held-out values landing inside the 95% band.
-100%Change by 2029
0.00Projected 2029 index
0.00–5.495% range
±119.8%Backtest error
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.14 | 0.00 | 5.5 |
| 2026 | 0.01 | 0.00 | 5.4 |
| 2027 | 0.00 | 0.00 | 5.4 |
| 2028 | 0.00 | 0.00 | 5.4 |
| 2029 | 0.00 | 0.00 | 5.4 |
Routes In BCR 4
| Wasilla | ALASKA | 42 | 1983 |
| Cottonwood | ALASKA | 36 | 1990 |
| Skilak Lake | ALASKA | 21 | 1985 |
| Goose Bay | ALASKA | 20 | 1982 |
| Unalakleet River | ALASKA | 12 | 2023 |
| Hather Creek | ALASKA | 11 | 2024 |
| Galena (Short) | ALASKA | 11 | 2024 |
| Matanuska | ALASKA | 10 | 1983 |
| Chena Hot Sp | ALASKA | 9 | 1990 |
| Willow | ALASKA | 7 | 2024 |
| Kuskulana | ALASKA | 6 | 2023 |
| Slana | ALASKA | 5 | 2022 |
| Homer | ALASKA | 5 | 1982 |
| L Salcha | ALASKA | 5 | 2008 |
| Murphy Dome | ALASKA | 5 | 2017 |
| Northway | ALASKA | 4 | 2019 |
| Kalifonsky | ALASKA | 4 | 2023 |
| Sourdough | ALASKA | 4 | 2016 |
| Lake Louise | ALASKA | 4 | 2008 |
| Tangle Lakes | ALASKA | 4 | 1987 |
| Mud River | ALASKA | 4 | 2024 |
| Monahan | ALASKA | 3 | 2018 |
| Tonsina | ALASKA | 3 | 2021 |
| Bear Creek | ALASKA | 3 | 1991 |
| Anchor River | ALASKA | 3 | 2023 |
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.