BirdAnalyst
Species · BCR 15 · BBS 2025 Release · 1966–2024

White-throated Swift In Sierra Nevada

All regionsSierra NevadaAerial insectivores

White-throated Swift in Sierra Nevada has fallen sharply: down 64% on the route-weighted index since 1974.

-64%Since 1974TrendPercent 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 →
19Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
51YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 →

White-throated Swift has fallen sharply in Sierra Nevada: down 64% on the route-weighted index since 1974.

White-throated Swift In Sierra Nevada Population Forecast

If the recent trend holds, White-throated Swift in Sierra Nevada is projected to fall about 84% by 2029 — from 2.1 in 2024 to a central estimate of 0.34 (95% range 0.00–7.6). A 5-year backtest shows a typical error of ±83.2%, with 100% of held-out values landing inside the 95% band.

-84%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 →
0.34Projected 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 →
0.00–7.695% 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 →
±83.2%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, White-throated Swift in Sierra Nevada is projected to fall about 84% by 2029 — from 2.1 in 2024 to a central estimate of 0.34 (95% range 0.00–7.6). A 5-year backtest shows a typical error of ±83.2%, with 100% of held-out values landing inside the 95% band.19722029
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 →
20250.890.008.2
20260.750.008.0
20270.610.007.9
20280.470.007.8
20290.340.007.6

Routes In Sierra Nevada

Routes recording White-throated Swift in Sierra Nevada.
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 →
Kings CanyonCALIFORNIA312024
KernvilleCALIFORNIA202008
Silver CityCALIFORNIA112013
WawonaCALIFORNIA72024
Hat CreekCALIFORNIA62000
DardanelleCALIFORNIA31974
Lassen ParkCALIFORNIA21981
Bass LakeCALIFORNIA22019
WoodfordsCALIFORNIA22021
Tuolumne GroveCALIFORNIA22024
Forest HillCALIFORNIA22009
Higgins CornCALIFORNIA11973
DownievilleCALIFORNIA11975
RivertonCALIFORNIA11974
LakeshoreCALIFORNIA12009
Chaos CraterCALIFORNIA11997
CoultervilleCALIFORNIA12008
CrestviewCALIFORNIA12021
StrawberryCALIFORNIA12018

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