Mourning Warbler
Mourning Warbler has held roughly steady: up 8% on the route-weighted index since 1968.
About the Mourning Warbler
The Mourning Warbler (Geothlypis philadelphia) 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 437 Breeding Bird Survey routes across 16 states, most concentrated in the Boreal Hardwood Transition.
- Family
- Parulidae · Forest birds
Notable Mourning Warbler Trends
No notable trend signals for Mourning Warbler. See the full index history below.
Mourning Warbler Population Forecast
If the recent trend holds, Mourning Warbler is projected to stay roughly flat through 2029, near 0.23 (95% range 0.12–0.35). A 5-year backtest shows a typical error of ±14%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.24 | 0.12 | 0.36 |
| 2026 | 0.24 | 0.12 | 0.36 |
| 2027 | 0.24 | 0.12 | 0.35 |
| 2028 | 0.23 | 0.12 | 0.35 |
| 2029 | 0.23 | 0.12 | 0.35 |
Where the Mourning Warbler Is Detected
BBS routes recording Mourning Warbler, sized by most recent count.
Mourning Warbler Population Trend by State
| Connecticut | insufficient data | n/a | 1 |
| Illinois | insufficient data | n/a | 1 |
| Indiana | insufficient data | n/a | 1 |
| Maine | -72% | 1974 | 54 |
| Maryland | insufficient data | n/a | 3 |
| Massachusetts | -18% | 1987 | 4 |
| Michigan | +260% | 1968 | 74 |
| Minnesota | +28% | 1969 | 45 |
| New Hampshire | +69% | 1969 | 12 |
| New York | +3% | 1968 | 88 |
| North Dakota | insufficient data | n/a | 2 |
| Ohio | insufficient data | n/a | 1 |
| Pennsylvania | -14% | 1968 | 34 |
| Vermont | +502% | 1969 | 25 |
| West Virginia | +229% | 1976 | 12 |
| Wisconsin | +35% | 1968 | 80 |
Mourning Warbler Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Prairie Potholes | -38% | 1981 | 7 |
| Boreal Hardwood Transition | +48% | 1968 | 122 |
| Lower Great Lakes / St. Lawrence Plain | -44% | 1968 | 50 |
| Atlantic Northern Forest | -2% | 1968 | 117 |
| Prairie Hardwood Transition | -39% | 1968 | 72 |
| Appalachian Mountains | +60% | 1968 | 66 |
Mourning Warbler Conservation Status
Our route-weighted index shows it up about 8% 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.