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Species · Utah · BBS 2025 Release · 1966–2024

Violet-green Swallow Population Trend in Utah

All statesAerial insectivores

Violet-green Swallow in Utah has surged: up 114% on the route-weighted index since 1970.

+114%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 →
94Routes 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 →
56YearsYears 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 UtahNotable 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 Utah: up 114% on the route-weighted index since 1970.

Violet-green Swallow Population Forecast in Utah

If the recent trend holds, Violet-green Swallow in Utah is projected to rise about 38% by 2029 — from 2.5 in 2024 to a central estimate of 3.4 (95% range 0.00–7.2). A 5-year backtest shows a typical error of ±37.4%, with 100% of held-out values landing inside the 95% band.

+38%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 →
3.4Projected 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 →
0.00–7.295% 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 →
±37.4%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 Utah is projected to rise about 38% by 2029 — from 2.5 in 2024 to a central estimate of 3.4 (95% range 0.00–7.2). A 5-year backtest shows a typical error of ±37.4%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20253.50.007.3
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Violet-green Swallow Survey Routes in Utah

Routes recording Violet-green Swallow in Utah.
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 →
Bryce Canyon3720241990
Boulder3420211971
Hyrum3319791975
La Sal2920001994
Hardware Ranch2820181994
Canyonlands2620061991
Pine Creek2520131998
Main Canyon2120241987
La Sal 22020062003
Moab1720241986
Randolph1620241992
Hill Creek1519951993
Hite1420231986
Alton1420191998
Arches Np1320101989
Glen Canyon1220221992
Logan Canyon1120191997
Newcastle1020221997
Hanna920241997
Ant Flat-Ogden Can820231997
Lake Powell820091993
Book Ridge720182003
Woodruff720242002
Wasatch Nf620212002
Moon Lake620021993

Violet-green Swallow Population Trend in Other States

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Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22.