BirdAnalyst
Species · BCR 15 · BBS 2026 Release · 1966–2025

Wilson's Warbler In Sierra Nevada

All regionsSierra NevadaForest birds

Wilson's Warbler in Sierra Nevada has fallen sharply: down 58% on the route-weighted index since 1970.

-58%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 →
33Routes 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 →
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 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 →

Wilson's Warbler has fallen sharply in Sierra Nevada: down 58% on the route-weighted index since 1970.

Wilson's Warbler In Sierra Nevada Population Forecast

If the recent trend holds, Wilson's Warbler in Sierra Nevada is projected to fall about 20% by 2030 — from 0.72 in 2025 to a central estimate of 0.58 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±14.8%, with 100% of held-out values landing inside the 95% band.

-20%Change by 2030TrendPercent 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 →
0.58Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1.895% 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 →
±14.8%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, Wilson's Warbler in Sierra Nevada is projected to fall about 20% by 2030 — from 0.72 in 2025 to a central estimate of 0.58 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±14.8%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.670.001.9
20270.640.001.9
20280.620.001.9
20290.600.001.8
20300.580.001.8

Routes In Sierra Nevada

Routes recording Wilson's Warbler 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 →
GeneseeCALIFORNIA102024
ChesterCALIFORNIA102017
Last ChanceCALIFORNIA72019
Greenhorn MtCALIFORNIA61982
DardanelleCALIFORNIA52019
Lassen ParkCALIFORNIA31977
WestvilleCALIFORNIA32021
Silver CityCALIFORNIA32005
PaxtonCALIFORNIA32025
Meadow ValleyCALIFORNIA32025
Cottage SpgsCALIFORNIA21970
WoodfordsCALIFORNIA22025
Kings CanyonCALIFORNIA21987
Butte MeadowCALIFORNIA22014
CoultervilleCALIFORNIA22018
Eagle LakeCALIFORNIA12005
Bass LakeCALIFORNIA12019
JohnsvilleCALIFORNIA12025
LumberyardCALIFORNIA12025
Tuolumne GroveCALIFORNIA12011
SattleyCALIFORNIA12016
Higgins CornCALIFORNIA12013
DownievilleCALIFORNIA12025
RivertonCALIFORNIA12025
Hat CreekCALIFORNIA12016

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.