Chestnut-sided Warbler
Chestnut-sided Warbler has edged down: down 11% on the route-weighted index since 1968.
About the Chestnut-sided Warbler
The Chestnut-sided Warbler (Setophaga pensylvanica) 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 847 Breeding Bird Survey routes across 30 states, most concentrated in the Appalachian Mountains.
- Family
- Parulidae · Forest birds
Notable Chestnut-sided Warbler Trends
No notable trend signals for Chestnut-sided Warbler. See the full index history below.
Chestnut-sided Warbler Population Forecast
If the recent trend holds, Chestnut-sided Warbler is projected to fall about 23% by 2029 — from 1.3 in 2024 to a central estimate of 1.0 (95% range 0.76–1.3). A 5-year backtest shows a typical error of ±20.9%, with 40% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 1.1 | 0.79 | 1.4 |
| 2026 | 1.1 | 0.78 | 1.3 |
| 2027 | 1.1 | 0.77 | 1.3 |
| 2028 | 1.0 | 0.76 | 1.3 |
| 2029 | 1.0 | 0.76 | 1.3 |
Where the Chestnut-sided Warbler Is Detected
BBS routes recording Chestnut-sided Warbler, sized by most recent count.
Chestnut-sided Warbler Population Trend by State
| Alabama | insufficient data | n/a | 2 |
| Arkansas | +23% | 2007 | 6 |
| Colorado | insufficient data | n/a | 1 |
| Connecticut | -62% | 1968 | 20 |
| Georgia | insufficient data | n/a | 2 |
| Illinois | insufficient data | n/a | 6 |
| Indiana | -21% | 1981 | 12 |
| Iowa | insufficient data | n/a | 2 |
| Kansas | insufficient data | n/a | 1 |
| Kentucky | insufficient data | n/a | 3 |
| Maine | +9% | 1968 | 77 |
| Maryland | +114% | 1968 | 13 |
| Massachusetts | +50% | 1968 | 28 |
| Michigan | +100% | 1968 | 92 |
| Minnesota | +57% | 1969 | 56 |
| Nevada | insufficient data | n/a | 1 |
| New Hampshire | +4% | 1968 | 26 |
| New Jersey | +47% | 1970 | 20 |
| New York | +76% | 1968 | 123 |
| North Carolina | -11% | 1970 | 24 |
| North Dakota | insufficient data | n/a | 1 |
| Ohio | +78% | 1976 | 20 |
| Pennsylvania | +107% | 1968 | 112 |
| Rhode Island | -63% | 1968 | 6 |
| Tennessee | +19% | 1968 | 10 |
| Vermont | +42% | 1968 | 26 |
| Virginia | +402% | 1969 | 27 |
| West Virginia | +365% | 1968 | 41 |
| Wisconsin | +114% | 1968 | 87 |
| Wyoming | insufficient data | n/a | 2 |
Chestnut-sided Warbler Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Prairie Potholes | -53% | 1979 | 9 |
| Boreal Hardwood Transition | +74% | 1968 | 124 |
| Lower Great Lakes / St. Lawrence Plain | +88% | 1968 | 78 |
| Atlantic Northern Forest | +15% | 1968 | 155 |
| Eastern Tallgrass Prairie | -16% | 1983 | 14 |
| Prairie Hardwood Transition | +87% | 1968 | 109 |
| Central Hardwoods | -37% | 1999 | 10 |
| Appalachian Mountains | +117% | 1968 | 261 |
| Piedmont | -75% | 1971 | 19 |
| New England / Mid-Atlantic Coast | -41% | 1968 | 62 |
Chestnut-sided Warbler Conservation Status
Our route-weighted index shows it down about 11% 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.