Bay-breasted Warbler
Bay-breasted Warbler has collapsed: down 87% on the route-weighted index since 1968.
About the Bay-breasted Warbler
The Bay-breasted Warbler (Setophaga castanea) is a North American member of the Wood-Warblers (Parulidae). In this analysis it is grouped with the forest birds.
- Size
- 4.5–5.5 in long (11–14 cm) — a small, active songbird (typical for the family)
- Habitat
- Woodlands and forest edges, including wooded suburbs and parks.
- Diet
- Insects and spiders gleaned from foliage and bark, with seeds and berries in season.
- Range
- Recorded on 117 Breeding Bird Survey routes across 8 states, most concentrated in the Atlantic Northern Forest.
- Family
- Parulidae · Forest birds
Notable Bay-breasted Warbler Trends
No notable trend signals for Bay-breasted Warbler. See the full index history below.
Bay-breasted Warbler Population Forecast
If the recent trend holds, Bay-breasted Warbler is projected to stay roughly flat through 2029, near 0.00 (95% range 0.00–0.02). A 5-year backtest shows a typical error of ±46.6%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.00 | 0.00 | 0.02 |
| 2026 | 0.00 | 0.00 | 0.02 |
| 2027 | 0.00 | 0.00 | 0.02 |
| 2028 | 0.00 | 0.00 | 0.02 |
| 2029 | 0.00 | 0.00 | 0.02 |
Where the Bay-breasted Warbler Is Detected
BBS routes recording Bay-breasted Warbler, sized by most recent count.
Bay-breasted Warbler Population Trend by State
| Maine | -74% | 1971 | 57 |
| Michigan | +68% | 1987 | 16 |
| Minnesota | -56% | 1976 | 13 |
| New Hampshire | -82% | 1968 | 12 |
| New York | -13% | 1974 | 14 |
| Pennsylvania | insufficient data | n/a | 1 |
| Vermont | insufficient data | n/a | 3 |
| Wisconsin | insufficient data | n/a | 1 |
Bay-breasted Warbler Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Boreal Hardwood Transition | -14% | 1976 | 30 |
| Atlantic Northern Forest | -82% | 1968 | 85 |
Bay-breasted Warbler Conservation Status
Our route-weighted index shows it down about 87% since 1968.
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.