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Species · Montana · BBS 2026 Release · 1966–2025

Violet-green Swallow Population Trend in Montana

All statesAerial insectivores

Violet-green Swallow in Montana has surged: up 94% on the route-weighted index since 1970.

+94%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 →
57Routes 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 MontanaNotable 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 Montana: up 94% on the route-weighted index since 1970.

Violet-green Swallow Population Forecast in Montana

If the recent trend holds, Violet-green Swallow in Montana is projected to rise about 337% by 2030 — from 0.45 in 2025 to a central estimate of 1.9 (95% range 0.00–4.1). A 5-year backtest shows a typical error of ±458.9%, with 60% of held-out values landing inside the 95% band.

+337%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 →
1.9Projected 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 →
0.00–4.195% 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 →
±458.9%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 Montana is projected to rise about 337% by 2030 — from 0.45 in 2025 to a central estimate of 1.9 (95% range 0.00–4.1). A 5-year backtest shows a typical error of ±458.9%, with 60% 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 →
20261.90.004.0
20271.90.004.0
20281.90.004.0
20291.90.004.0
20301.90.004.1

Violet-green Swallow Survey Routes in Montana

Routes recording Violet-green Swallow in Montana.
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 →
Willow Creek 22120181987
St Xavier1820102001
Laurel920081972
Sula820142013
Pagil Gulch720232023
Cleveland620052004
Pryor Mtn.620252000
Greenoagh 2620092009
Philipsburg620252015
Libby Dam520251979
Great Falls519731972
Maynard Coulee520242021
Lima520251994
Elevation Mt420002000
Bull Mtn.420211999
Jordan420181988
Ninemile420251994
Noxon420232002
Wolf Creek320172017
Brunzell Slough320252021
Hebgen Lake320222017
Painted Rock320221992
Logan Pass220251980
St Regis220241986
Polson220091981

Violet-green Swallow Population Trend in Other States

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