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

Tree Swallow Population Trend in Washington

All statesAerial insectivores

Tree Swallow in Washington has held roughly steady: down 2% on the route-weighted index since 1970.

-2%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 →
94Routes 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 WashingtonNotable 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 Washington. See the full index history below.

Tree Swallow Population Forecast in Washington

If the recent trend holds, Tree Swallow in Washington is projected to rise about 81% by 2030 — from 2.6 in 2025 to a central estimate of 4.8 (95% range 2.5–7.0). A 5-year backtest shows a typical error of ±91.2%, with 40% of held-out values landing inside the 95% band.

+81%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 →
4.8Projected 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 →
2.5–7.095% 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 →
±91.2%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 Washington is projected to rise about 81% by 2030 — from 2.6 in 2025 to a central estimate of 4.8 (95% range 2.5–7.0). A 5-year backtest shows a typical error of ±91.2%, with 40% 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 →
20264.72.57.0
20274.72.57.0
20284.82.57.0
20294.82.57.0
20304.82.57.0

Tree Swallow Survey Routes in Washington

Routes recording Tree Swallow in Washington.
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 →
Twisp3020241969
Camas2820091971
Cougar2620231968
Harrington2520121972
Rainier1620191995
Wapato1320191978
Ellensburg1320251981
Mendota 31220252005
Deception1220181992
Leavenworth920241981
Ilwaco920251977
Carnation920251988
Asotin820251992
Bay View820171993
Mcchord820151996
Port Angeles720251970
Warm Beach720171968
Brewster720141978
Snowden720251972
Nighthawk720251992
Hurricane Rg720092001
Laurier720251996
Turnbull Nwr720231993
Curlew620181992
Pomeroy620242000

Tree Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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