BirdAnalyst
Species · Colorado · BBS 2026 Release · 1966–2025

Violet-green Swallow Population Trend in Colorado

All statesAerial insectivores

Violet-green Swallow in Colorado has risen sharply: up 70% on the route-weighted index since 1970.

+70%Since 1970TrendPercent 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 →
110Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Violet-green Swallow Trends in ColoradoNotable 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 risen sharply in Colorado: up 70% on the route-weighted index since 1970.

Violet-green Swallow Population Forecast in Colorado

If the recent trend holds, Violet-green Swallow in Colorado is projected to stay roughly flat through 2030, near 9.2 (95% range 2.7–16). A 5-year backtest shows a typical error of ±24.3%, with 100% of held-out values landing inside the 95% band.

-8%Change by 2030TrendPercent 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 →
9.2Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
2.7–1695% 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 →
±24.3%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 in Colorado is projected to stay roughly flat through 2030, near 9.2 (95% range 2.7–16). A 5-year backtest shows a typical error of ±24.3%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20269.12.616
20279.12.616
20289.12.616
20299.22.716
20309.22.716

Violet-green Swallow Survey Routes in Colorado

Routes recording Violet-green Swallow in Colorado.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Aspen9420251979
Dolores Riv7220251988
Mesaverde Np6820251996
Tarryall6020251988
Blackhead Pk6020251991
Rifle Falls5520251998
Dunckley Pas4420251992
Stillwater Pass4020091998
Fox Creek3620251993
Pagosa Spgs3519821968
Colona3320141972
Cokedale3120251995
Gold Hill2620121998
Buford2520251973
Owl Creek Pass2520251998
Parlin2420251968
Colona 22220252015
Baxter Pass2220241994
South Fork2220251994
Elbert2220251998
Lake City 22120252016
Gold Hill 22120252018
Douglas Pass1920241982
Mcphee Res.1920251996
Animas 21920252005

Violet-green Swallow Population Trend in Other States

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Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.