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

Bewick's Wren In Sierra Nevada

All regionsSierra NevadaForest birds

Bewick's Wren in Sierra Nevada has fallen sharply: down 69% on the route-weighted index since 1970.

-69%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 →
57YearsYears 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 →

Bewick's Wren has fallen sharply in Sierra Nevada: down 69% on the route-weighted index since 1970.

Bewick's Wren In Sierra Nevada Population Forecast

If the recent trend holds, Bewick's Wren in Sierra Nevada is projected to fall about 35% by 2030 — from 1.2 in 2025 to a central estimate of 0.79 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±74.2%, with 100% of held-out values landing inside the 95% band.

-35%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 →
0.79Projected 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 →
0.00–2.495% 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 →
±74.2%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, Bewick's Wren in Sierra Nevada is projected to fall about 35% by 2030 — from 1.2 in 2025 to a central estimate of 0.79 (95% range 0.00–2.4). A 5-year backtest shows a typical error of ±74.2%, 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 →
20260.860.002.5
20270.840.002.5
20280.830.002.5
20290.810.002.4
20300.790.002.4

Routes In Sierra Nevada

Routes recording Bewick's Wren 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 →
Silver CityCALIFORNIA152013
Forest HillCALIFORNIA112025
Cottage SpgsCALIFORNIA101974
Meadow ValleyCALIFORNIA42021
WawonaCALIFORNIA42025
Tuolumne GroveCALIFORNIA32025
RivertonCALIFORNIA32022
ChesterCALIFORNIA32017
Kings CanyonCALIFORNIA22024
SattleyCALIFORNIA21994
Butte MeadowCALIFORNIA22012
GeneseeCALIFORNIA22023
Lassen ParkCALIFORNIA11986
Eagle LakeCALIFORNIA12024
WestvilleCALIFORNIA12023
Bass LakeCALIFORNIA12019
JohnsvilleCALIFORNIA11985
WoodfordsCALIFORNIA12018
LumberyardCALIFORNIA12025
Greenhorn MtCALIFORNIA12008
Higgins CornCALIFORNIA12025
DownievilleCALIFORNIA12025
Hat CreekCALIFORNIA12017
LakeshoreCALIFORNIA12006
Tahoe NfCALIFORNIA11993

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