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

Vaux's Swift Population Trend in Washington

All statesAerial insectivores

Vaux's Swift in Washington has risen sharply: up 53% on the route-weighted index since 1970.

+53%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 →
71Routes 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 Vaux's Swift 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 →

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 →

Vaux's Swift has risen sharply in Washington: up 52% on the route-weighted index since 1970.

Vaux's Swift Population Forecast in Washington

If the recent trend holds, Vaux's Swift in Washington is projected to fall about 37% by 2029 — from 0.96 in 2024 to a central estimate of 0.61 (95% range 0.00–2.0). A 5-year backtest shows a typical error of ±43.5%, with 100% of held-out values landing inside the 95% band.

-37%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 →
0.61Projected 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 →
0.00–2.095% 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 →
±43.5%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, Vaux's Swift in Washington is projected to fall about 37% by 2029 — from 0.96 in 2024 to a central estimate of 0.61 (95% range 0.00–2.0). A 5-year backtest shows a typical error of ±43.5%, 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 →
20250.650.002.0
20260.640.002.0
20270.630.002.0
20280.620.002.0
20290.610.002.0

Vaux's Swift Survey Routes in Washington

Routes recording Vaux's Swift 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 →
Kendall1920241983
Cougar1120231969
Mcchord1020082004
Glacier920241976
Index 2820232015
Packwood720221975
Leavenworth620231984
Mukilteo620231995
Carnation620181990
Index519711968
Asotin519981998
Twin Lakes519901990
Ronald520181973
Raymond 2520222022
Mt St Helens520241992
Twisp420241971
Cusick420241990
Greenwater420222015
Issaquah319841969
Snowden320231982
Carlton320211992
Waitsburg320031994
Mt Rainier320191990
Mt. Adams320241994
Port Angeles220231981

Vaux's Swift Population Trend in Other States

alaskacaliforniaidahomontanaoregon

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