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

White-crowned Sparrow In Sierra Nevada

All regionsSierra NevadaGeneralists

White-crowned Sparrow in Sierra Nevada has collapsed: down 86% on the route-weighted index since 1973.

-86%Since 1973TrendPercent 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 →
17Routes 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 →
52YearsYears 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-crowned Sparrow has collapsed in Sierra Nevada: down 86% on the route-weighted index since 1973.

White-crowned Sparrow In Sierra Nevada Population Forecast

If the recent trend holds, White-crowned Sparrow in Sierra Nevada is projected to rise about 137% by 2028 — from 0.18 in 2023 to a central estimate of 0.42 (95% range 0.00–1.3). A 5-year backtest shows a typical error of ±100.5%, with 100% of held-out values landing inside the 95% band.

+137%Change by 2028TrendPercent 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 →
0.42Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1.395% 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 →
±100.5%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, White-crowned Sparrow in Sierra Nevada is projected to rise about 137% by 2028 — from 0.18 in 2023 to a central estimate of 0.42 (95% range 0.00–1.3). A 5-year backtest shows a typical error of ±100.5%, with 100% of held-out values landing inside the 95% band.19682028
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 →
20240.450.001.3
20250.440.001.3
20260.430.001.3
20270.420.001.3
20280.420.001.3

Routes In Sierra Nevada

Routes recording White-crowned Sparrow 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 →
Last ChanceCALIFORNIA62019
DardanelleCALIFORNIA42019
Cottage SpgsCALIFORNIA31968
JohnsvilleCALIFORNIA32019
ChesterCALIFORNIA22017
Lassen ParkCALIFORNIA11981
WestvilleCALIFORNIA12022
WoodfordsCALIFORNIA12023
Silver CityCALIFORNIA11977
Kings CanyonCALIFORNIA11972
SattleyCALIFORNIA11991
GeneseeCALIFORNIA11979
RivertonCALIFORNIA12010
LakeshoreCALIFORNIA12004
Little TruckeeCALIFORNIA12023
Pine MountainCALIFORNIA12017
ChilcootCALIFORNIA12023

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