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

Tree Swallow Population Trend in Washington

All statesAerial insectivores

Tree Swallow in Washington has held roughly steady: down 7% on the route-weighted index since 1970.

-7%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 →
93Routes 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 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 30% by 2029 — from 3.8 in 2024 to a central estimate of 4.9 (95% range 2.7–7.2). A 5-year backtest shows a typical error of ±69%, with 60% of held-out values landing inside the 95% band.

+30%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 →
4.9Projected 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 →
2.7–7.295% 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 →
±69%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 30% by 2029 — from 3.8 in 2024 to a central estimate of 4.9 (95% range 2.7–7.2). A 5-year backtest shows a typical error of ±69%, with 60% 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 →
20254.92.77.1
20264.92.77.1
20274.92.77.1
20284.92.77.1
20294.92.77.2

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
Nighthawk2320241992
Ilwaco1720241977
Rainier1620191995
Wapato1320191978
Laurier1320221996
Deception1220181992
Wilbur1020242001
Northport1020241996
Leavenworth920241981
Bay View820171993
L. Wenatchee820241994
Mcchord820151996
Warm Beach720171968
Brewster720141978
Rimrock720241968
Kendall720241981
Hurricane Rg720092001
Mendota 3720242005
Turnbull Nwr720231993
Snowden620241972
Everett620241975

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 2026-05-22.