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Species · Arizona · BBS 2025 Release · 1966–2024

Violet-green Swallow Population Trend in Arizona

All statesAerial insectivores

Violet-green Swallow in Arizona has risen sharply: up 63% on the route-weighted index since 1970.

+63%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 →
51Routes 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 ArizonaNotable 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 Arizona: up 63% on the route-weighted index since 1970.

Violet-green Swallow Population Forecast in Arizona

If the recent trend holds, Violet-green Swallow in Arizona is projected to fall about 14% by 2029 — from 6.1 in 2024 to a central estimate of 5.3 (95% range 2.4–8.1). A 5-year backtest shows a typical error of ±14.4%, with 100% of held-out values landing inside the 95% band.

-14%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 →
5.3Projected 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 →
2.4–8.195% 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 →
±14.4%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 Arizona is projected to fall about 14% by 2029 — from 6.1 in 2024 to a central estimate of 5.3 (95% range 2.4–8.1). A 5-year backtest shows a typical error of ±14.4%, 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 →
20255.22.38.0
20265.22.38.1
20275.22.48.1
20285.22.48.1
20295.32.48.1

Violet-green Swallow Survey Routes in Arizona

Routes recording Violet-green Swallow in Arizona.
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 →
Happy Jack10220241977
Dry Park6820241992
Alpine6520231992
Bartlett Res3020172009
Forest Lakes2820241992
Rucker2720011995
Blue2519911974
Pinetop2520221993
Tsaile2420231993
Aztec Peak2319781974
Sprucedale2220231992
Williams2020191993
Laguna1719861986
Maine1620241992
Peach Spring1620071996
Sawmill1520141988
Mormon Lake1319751968
Flagstaff920221988
Cow Springs920211993
Prescott720221975
San Simon619821974
Sunizona619961970
Clay Spring520091988
Round Rock419761968
Mt. Graham420231995

Violet-green Swallow Population Trend in Other States

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