Violet-green Swallow
Violet-green Swallow has surged: up 197% on the route-weighted index since 1969.
About the Violet-green Swallow
The Violet-green Swallow (Tachycineta thalassina) is a North American member of the Swallows & Martins (Hirundinidae). In this analysis it is grouped with the aerial insectivores.
- Size
- 4.5–8 in long (12–20 cm) — a small, streamlined bird (typical for the family)
- Habitat
- Open airspace over fields, water and towns; nests in cavities, earthen banks or on structures.
- Diet
- Flying insects caught on the wing.
- Range
- Recorded on 1,059 Breeding Bird Survey routes across 16 states, most concentrated in the Southern Rockies / Colorado Plateau.
- Family
- Hirundinidae · Aerial insectivores
Notable Violet-green Swallow Trends
Violet-green Swallow has surged in surveyed states: up 197% on the route-weighted index since 1969.
Violet-green Swallow Population Forecast
If the recent trend holds, Violet-green Swallow is projected to rise about 23% by 2029 — from 1.4 in 2024 to a central estimate of 1.7 (95% range 1.1–2.3). A 5-year backtest shows a typical error of ±37.8%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 1.7 | 1.1 | 2.3 |
| 2026 | 1.7 | 1.1 | 2.3 |
| 2027 | 1.7 | 1.1 | 2.3 |
| 2028 | 1.7 | 1.1 | 2.3 |
| 2029 | 1.7 | 1.1 | 2.3 |
Where the Violet-green Swallow Is Detected
BBS routes recording Violet-green Swallow, sized by most recent count.
Violet-green Swallow Population Trend by State
| Alaska | +51% | 1978 | 80 |
| Arizona | +63% | 1970 | 51 |
| California | -62% | 1970 | 184 |
| Colorado | +46% | 1970 | 109 |
| Idaho | -32% | 1970 | 56 |
| Montana | +69% | 1970 | 56 |
| Nebraska | -39% | 1999 | 4 |
| Nevada | -70% | 1970 | 32 |
| New Mexico | -36% | 1970 | 54 |
| North Dakota | insufficient data | n/a | 1 |
| Oregon | -27% | 1970 | 112 |
| South Dakota | +19% | 1969 | 18 |
| Texas | -55% | 1975 | 10 |
| Utah | +114% | 1970 | 94 |
| Washington | -16% | 1970 | 102 |
| Wyoming | +215% | 1973 | 96 |
Violet-green Swallow Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| BCR 4 | +70% | 1978 | 53 |
| Northern Pacific Rainforest | -28% | 1970 | 136 |
| Great Basin | -14% | 1970 | 189 |
| Northern Rockies | +9% | 1970 | 184 |
| Sierra Nevada | -81% | 1972 | 29 |
| Southern Rockies / Colorado Plateau | +36% | 1970 | 228 |
| Badlands and Prairies | -44% | 1969 | 49 |
| Shortgrass Prairie | +176% | 1993 | 16 |
| Coastal California | -60% | 1970 | 94 |
| Sonoran and Mojave Deserts | -72% | 1973 | 20 |
| Sierra Madre Occidental | +23% | 1970 | 32 |
| Chihuahuan Desert | +31% | 1975 | 21 |
Violet-green Swallow Conservation Status
Our route-weighted index shows it up about 197% since 1969. Aerial insectivores have fallen sharply across the continent, a decline widely linked to dwindling insect prey.
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.