BirdAnalyst
Species · BBS 2025 Release · 1966–2024

Violet-green Swallow

HirundinidaeAerial insectivoresTachycineta thalassina

Violet-green Swallow has surged: up 197% on the route-weighted index since 1969.

+197%Since 1969TrendPercent 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 →
1,059RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

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 TrendsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed indexTrend sourceWhether the figure is our own computed route-weighted index or an official USGS modeled estimate. The current build labels every trend as computed.Full methodology →

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.

+23%Change by 2029TrendPercent 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 →
1.7Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
1.1–2.395% range95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
±37.8%Backtest errorBacktest errorTypical error when we hold out the most recent years, forecast them, and compare to what actually happened. Lower means a more trustworthy projection.Full methodology →
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.19672029
Projection of the recent trend (dashed) with 80/95% bands — a projection, not a prediction. Habitat, climate, and land use are not modeled.
YearProjected indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →95% low95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →95% high95% rangeThe 95% uncertainty band around the projection at the forecast horizon. The true value should land inside it most of the time.Full methodology →
20251.71.12.3
20261.71.12.3
20271.71.12.3
20281.71.12.3
20291.71.12.3

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

Violet-green Swallow 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+51%197880
Arizona+63%197051
California-62%1970184
Colorado+46%1970109
Idaho-32%197056
Montana+69%197056
Nebraska-39%19994
Nevada-70%197032
New Mexico-36%197054
North Dakotainsufficient datan/a1
Oregon-27%1970112
South Dakota+19%196918
Texas-55%197510
Utah+114%197094
Washington-16%1970102
Wyoming+215%197396

Violet-green Swallow Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Violet-green Swallow population trend by Bird Conservation Region.
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 4+70%197853
Northern Pacific Rainforest-28%1970136
Great Basin-14%1970189
Northern Rockies+9%1970184
Sierra Nevada-81%197229
Southern Rockies / Colorado Plateau+36%1970228
Badlands and Prairies-44%196949
Shortgrass Prairie+176%199316
Coastal California-60%197094
Sonoran and Mojave Deserts-72%197320
Sierra Madre Occidental+23%197032
Chihuahuan Desert+31%197521

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.