Wilson's Warbler Population Analysis
Wilson's Warbler has surged: up 700% on the route-weighted index since 1968.
About the Wilson's Warbler
The Wilson's Warbler (Cardellina pusilla) 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 789 Breeding Bird Survey routes across 18 states, most concentrated in the Northern Pacific Rainforest.
- Family
- Parulidae · Forest birds
Notable Wilson's Warbler TrendsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →
Wilson's Warbler has surged in surveyed states: up 700% on the route-weighted index since 1968.
Wilson's Warbler Population Forecast
If the recent trend holds, Wilson's Warbler is projected to rise about 78% by 2030 — from 0.63 in 2025 to a central estimate of 1.1 (95% range 0.76–1.5). A 5-year backtest shows a typical error of ±57.9%, with 0% of held-out values landing inside the 95% band.
Where the Wilson's Warbler Is Detected
BBS routes recording Wilson's Warbler, sized by most recent count.
Wilson's Warbler Population Trend by State
| TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology → | Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology → | Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology → | |
|---|---|---|---|
| Alaska | +3% | 1972 | 129 |
| California | -55% | 1970 | 168 |
| Colorado | -23% | 1970 | 73 |
| Idaho | +279% | 1975 | 38 |
| Maine | -84% | 1969 | 43 |
| Michigan | insufficient data | n/a | 7 |
| Minnesota | -21% | 1986 | 12 |
| Montana | -18% | 1972 | 39 |
| Nevada | -21% | 1993 | 16 |
| New Hampshire | -68% | 1968 | 8 |
| New Mexico | insufficient data | n/a | 8 |
| New York | +65% | 1980 | 3 |
| Oregon | +25% | 1970 | 92 |
| Utah | -82% | 1977 | 29 |
| Vermont | insufficient data | n/a | 3 |
| Washington | -34% | 1970 | 84 |
| Wisconsin | insufficient data | n/a | 1 |
| Wyoming | -43% | 1970 | 36 |
Wilson's Warbler Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| TrendPercent change in the route-weighted abundance index between a smoothed baseline window and the most recent one. It tracks direction, not absolute population.Full methodology → | Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology → | Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology → | |
|---|---|---|---|
| BCR 2 | -40% | 1985 | 23 |
| BCR 3 | +84% | 1998 | 4 |
| BCR 4 | +20% | 1978 | 68 |
| Northern Pacific Rainforest | -12% | 1970 | 158 |
| Great Basin | +1% | 1970 | 110 |
| Northern Rockies | +0% | 1970 | 123 |
| Boreal Hardwood Transition | -18% | 1986 | 20 |
| Atlantic Northern Forest | -91% | 1968 | 57 |
| Sierra Nevada | -58% | 1970 | 33 |
| Southern Rockies / Colorado Plateau | +41% | 1970 | 104 |
| Coastal California | +118% | 1971 | 77 |
| Sonoran and Mojave Deserts | -49% | 1973 | 6 |
Wilson's Warbler Conservation Status
Our route-weighted index shows it up about 700% since 1968.
Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14. Trend is a route-weighted relative-abundance index, not an absolute population.