Ruby-crowned Kinglet
Ruby-crowned Kinglet has surged: up 12× on the route-weighted index since 1968.
About the Ruby-crowned Kinglet
The Ruby-crowned Kinglet (Corthylio calendula) is a North American member of the Kinglets (Regulidae). In this analysis it is grouped with the forest birds.
- Size
- 3.5–4.5 in long (9–11 cm) — a tiny 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 797 Breeding Bird Survey routes across 20 states, most concentrated in the Northern Rockies.
- Family
- Regulidae · Forest birds
Notable Ruby-crowned Kinglet Trends
Ruby-crowned Kinglet has surged in surveyed states: up 12× on the route-weighted index since 1968.
Ruby-crowned Kinglet Population Forecast
If the recent trend holds, Ruby-crowned Kinglet is projected to rise about 64% by 2029 — from 0.95 in 2024 to a central estimate of 1.6 (95% range 1.1–2.0). A 5-year backtest shows a typical error of ±48%, with 20% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 1.5 | 1.00 | 1.9 |
| 2026 | 1.5 | 1.0 | 1.9 |
| 2027 | 1.5 | 1.0 | 2.0 |
| 2028 | 1.5 | 1.1 | 2.0 |
| 2029 | 1.6 | 1.1 | 2.0 |
Where the Ruby-crowned Kinglet Is Detected
BBS routes recording Ruby-crowned Kinglet, sized by most recent count.
Ruby-crowned Kinglet Population Trend by State
| Alaska | +128% | 1978 | 106 |
| Arizona | 24× | 1975 | 15 |
| California | -75% | 1970 | 58 |
| Colorado | +823% | 1970 | 74 |
| Idaho | +249% | 1970 | 43 |
| Maine | -89% | 1968 | 63 |
| Michigan | +1% | 1971 | 35 |
| Minnesota | +2% | 1969 | 34 |
| Montana | +51% | 1970 | 52 |
| Nevada | insufficient data | n/a | 2 |
| New Hampshire | -23% | 1968 | 15 |
| New Mexico | +53% | 1971 | 14 |
| New York | -11% | 1968 | 27 |
| Oregon | -31% | 1970 | 63 |
| South Dakota | 13× | 1975 | 12 |
| Utah | 13× | 1974 | 48 |
| Vermont | -78% | 1971 | 15 |
| Washington | +72% | 1971 | 48 |
| Wisconsin | -65% | 1969 | 25 |
| Wyoming | +405% | 1970 | 48 |
Ruby-crowned Kinglet Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| BCR 2 | -61% | 1993 | 7 |
| BCR 4 | +25% | 1982 | 65 |
| Northern Pacific Rainforest | 16× | 1970 | 81 |
| Great Basin | +43% | 1972 | 66 |
| Northern Rockies | +33% | 1970 | 154 |
| Boreal Hardwood Transition | -6% | 1969 | 88 |
| Lower Great Lakes / St. Lawrence Plain | -7% | 1972 | 7 |
| Atlantic Northern Forest | -61% | 1968 | 112 |
| Sierra Nevada | -84% | 1972 | 25 |
| Southern Rockies / Colorado Plateau | 17× | 1970 | 137 |
| Badlands and Prairies | 11× | 1975 | 20 |
| Sierra Madre Occidental | +656% | 1975 | 12 |
Ruby-crowned Kinglet Conservation Status
Our route-weighted index shows it up about 1117% 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.