BirdAnalyst
Species · Colorado · BBS 2026 Release · 1966–2025

Tree Swallow Population Trend in Colorado

All statesAerial insectivores

Tree Swallow in Colorado has edged up: up 22% on the route-weighted index since 1970.

+22%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 →
107Routes 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 →
57YearsYears 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 89% by 2030 — from 2.1 in 2025 to a central estimate of 4.0 (95% range 0.78–7.2). A 5-year backtest shows a typical error of ±101.2%, with 100% of held-out values landing inside the 95% band.

+89%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 →
4.0Projected 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 →
0.78–7.295% 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 →
±101.2%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 89% by 2030 — from 2.1 in 2025 to a central estimate of 4.0 (95% range 0.78–7.2). A 5-year backtest shows a typical error of ±101.2%, with 100% 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 →
20263.90.727.1
20273.90.747.1
20283.90.757.1
20294.00.767.2
20304.00.787.2

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
Weston Pass2120001995
Parlin2020251969
Pagosa Spgs1619781968
Lost Lake1620251990
Rio Grnds Rs1620241993
De Beque1520251992
Deadman Rd.1420251992
Trail Ridge Road1420142003
Steamboat L.1220251996
Heeney1220192017
Buford1120251970
Lake City1120001988
Gold Hill1120121998
Cortez1020081988
Cheesman Lk920251977
Tarryall920251988
Castleton920251988
Fox Creek920251993
Lake City 2920252016
Mcphee Res.920181997
Yellowjacket Pass920251998
Stillwater Pass820071999
Kiowa720181993
Kiowa 2720252019

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 2026-08-14.