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

Tree Swallow Population Trend in Colorado

All statesAerial insectivores

Tree Swallow in Colorado has increased: up 40% on the route-weighted index since 1970.

+40%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 →
106Routes 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 ColoradoNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Tree Swallow in Colorado. See the full index history below.

Tree Swallow Population Forecast in Colorado

If the recent trend holds, Tree Swallow in Colorado is projected to rise about 108% by 2029 — from 2.0 in 2024 to a central estimate of 4.1 (95% range 0.93–7.3). A 5-year backtest shows a typical error of ±85.9%, with 100% of held-out values landing inside the 95% band.

+108%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 →
4.1Projected 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 →
0.93–7.395% 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 →
±85.9%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, Tree Swallow in Colorado is projected to rise about 108% by 2029 — from 2.0 in 2024 to a central estimate of 4.1 (95% range 0.93–7.3). A 5-year backtest shows a typical error of ±85.9%, 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 →
20254.00.867.2
20264.10.887.2
20274.10.897.3
20284.10.917.3
20294.10.937.3

Tree Swallow Survey Routes in Colorado

Routes recording Tree 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 →
Yampa2320231969
Lake City 22220242016
Weston Pass2120001995
Elbert1920221998
Castleton1820241988
Pagosa Spgs1619781968
Rio Grnds Rs1620241993
Lost Lake1520241990
Cheesman Lk1420191977
Trail Ridge Road1420142003
Fox Creek1320241993
Moon Pass1320242014
Heeney1220192017
Lake City1120001988
Tincup1120241994
Gold Hill1120121998
Cortez1020081988
Gribbles Prk1020241995
Rosevale920242009
Mcphee Res.920181997
Tarryall820231988
Stillwater Pass820071999
Kiowa720181993
Kiowa 2720242019
Yellowjacket Pass720241998

Tree Swallow Population Trend in Other States

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

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