BirdAnalyst
Species · Montana · BBS 2025 Release · 1966–2024

Tree Swallow Population Trend in Montana

All statesAerial insectivores

Tree Swallow in Montana has surged: up 112% on the route-weighted index since 1970.

+112%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 →
100Routes 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 Tree 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 →

Tree Swallow has surged in Montana: up 112% on the route-weighted index since 1970.

Tree Swallow Population Forecast in Montana

If the recent trend holds, Tree Swallow in Montana is projected to rise about 19% by 2029 — from 6.2 in 2024 to a central estimate of 7.3 (95% range 5.2–9.4). A 5-year backtest shows a typical error of ±23.5%, with 80% of held-out values landing inside the 95% band.

+19%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 →
7.3Projected 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 →
5.2–9.495% 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 →
±23.5%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, Tree Swallow in Montana is projected to rise about 19% by 2029 — from 6.2 in 2024 to a central estimate of 7.3 (95% range 5.2–9.4). A 5-year backtest shows a typical error of ±23.5%, with 80% 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 →
20257.04.99.1
20267.15.09.2
20277.25.19.3
20287.25.19.4
20297.35.29.4

Tree Swallow Survey Routes in Montana

Routes recording Tree 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 →
Red Rock11520241973
St Xavier4520101991
Pablo Res.3920241995
Hebgen Lake3720242017
Chestnut2720241968
Clyde Park2420242018
Two Dot2120241976
Beaverhead2120241973
Kalispell1920241968
St. Mary 21920242009
Woodman1520241968
Elliston1520241968
Logan Pass1420241995
Ninemile1320241993
Philipsburg1220242015
Wise River1120241993
Freeman Creek1020162015
Fort Logan1020242018
Augusta920241978
Reed Point920241977
Clancy920232015
Polson820241979
Libby Dam720241979
Lima720241996
St Xavier 2720232018

Tree Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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