Hermit Warbler
Hermit Warbler has surged: up 333% on the route-weighted index since 1970.
About the Hermit Warbler
The Hermit Warbler (Setophaga occidentalis) 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 195 Breeding Bird Survey routes across 3 states, most concentrated in the Northern Pacific Rainforest.
- Family
- Parulidae · Forest birds
Notable Hermit Warbler Trends
Hermit Warbler has surged in surveyed states: up 333% on the route-weighted index since 1970.
Hermit Warbler Population Forecast
If the recent trend holds, Hermit Warbler is projected to rise about 50% by 2029 — from 0.31 in 2024 to a central estimate of 0.46 (95% range 0.27–0.66). A 5-year backtest shows a typical error of ±45.5%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.45 | 0.25 | 0.64 |
| 2026 | 0.45 | 0.25 | 0.65 |
| 2027 | 0.45 | 0.26 | 0.65 |
| 2028 | 0.46 | 0.26 | 0.66 |
| 2029 | 0.46 | 0.27 | 0.66 |
Where the Hermit Warbler Is Detected
BBS routes recording Hermit Warbler, sized by most recent count.
Hermit Warbler Population Trend by State
| California | +446% | 1970 | 109 |
| Oregon | +45% | 1970 | 59 |
| Washington | +1% | 1971 | 27 |
Hermit Warbler Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Northern Pacific Rainforest | +57% | 1970 | 104 |
| Great Basin | +14% | 1973 | 24 |
| Sierra Nevada | +109% | 1971 | 38 |
| Coastal California | +286% | 1973 | 23 |
Hermit Warbler Conservation Status
Our route-weighted index shows it up about 333% since 1970.
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.