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

Vaux's Swift Population Trend in Idaho

All statesAerial insectivores

Vaux's Swift in Idaho has collapsed: down 76% on the route-weighted index since 1978.

-76%Since 1978TrendPercent 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 →
20Routes 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 →
42YearsYears 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 IdahoNotable 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 declinecomputed 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 collapsed in Idaho: down 76% on the route-weighted index since 1978.

Vaux's Swift Population Forecast in Idaho

If the recent trend holds, Vaux's Swift in Idaho is projected to fall about 74% by 2029 — from 0.20 in 2024 to a central estimate of 0.05 (95% range 0.00–0.31). A 5-year backtest shows a typical error of ±82.9%, with 100% of held-out values landing inside the 95% band.

-74%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 →
0.05Projected 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 →
0.00–0.3195% 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 →
±82.9%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, Vaux's Swift in Idaho is projected to fall about 74% by 2029 — from 0.20 in 2024 to a central estimate of 0.05 (95% range 0.00–0.31). A 5-year backtest shows a typical error of ±82.9%, with 100% of held-out values landing inside the 95% band.19732029
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 →
20250.080.000.34
20260.070.000.33
20270.070.000.32
20280.060.000.32
20290.050.000.31

Vaux's Swift Survey Routes in Idaho

Routes recording Vaux's Swift in Idaho.
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 →
Baldy Mountain1220152015
Centerville820082008
Grangeville620071986
Coolin520242018
Naples220161973
Mivoden220221978
Lolo Pass220191992
Cascade219841984
Avery120231984
Gifford120091991
Nezperce120071992
Golden120091993
N Fork Cda R120161994
Rochat Divde120161996
Marble Creek120141988
Pierce120051990
Salmon River120181988
Burgdorf119891989
Crane Creek120072007
Cabarton119971987

Vaux's Swift Population Trend in Other States

alaskacaliforniamontanaoregonwashington

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