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

Williamson's Sapsucker In Sierra Nevada

All regionsSierra NevadaForest birds

Williamson's Sapsucker in Sierra Nevada has increased: up 35% on the route-weighted index since 1975.

+35%Since 1975TrendPercent 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 →
18Routes 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 →
43YearsYears 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 →

No notable trend signals for Williamson's Sapsucker in Sierra Nevada. See the full index history below.

Williamson's Sapsucker In Sierra Nevada Population Forecast

If the recent trend holds, Williamson's Sapsucker in Sierra Nevada is projected to rise about 312% by 2029 — from 0.10 in 2024 to a central estimate of 0.43 (95% range 0.11–0.76). A 5-year backtest shows a typical error of ±130.5%, with 80% of held-out values landing inside the 95% band.

+312%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 →
0.43Projected 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 →
0.11–0.7695% 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 →
±130.5%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, Williamson's Sapsucker in Sierra Nevada is projected to rise about 312% by 2029 — from 0.10 in 2024 to a central estimate of 0.43 (95% range 0.11–0.76). A 5-year backtest shows a typical error of ±130.5%, with 80% 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 →
20250.410.080.74
20260.420.090.74
20270.420.100.75
20280.430.100.76
20290.430.110.76

Routes In Sierra Nevada

Routes recording Williamson's Sapsucker 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 →
LakeshoreCALIFORNIA42004
Eagle LakeCALIFORNIA21985
DardanelleCALIFORNIA22004
Tuolumne GroveCALIFORNIA22014
DownievilleCALIFORNIA21975
GoumazCALIFORNIA22011
Little TruckeeCALIFORNIA22023
Pine MountainCALIFORNIA22017
CrestviewCALIFORNIA22024
Lassen ParkCALIFORNIA11976
WoodfordsCALIFORNIA12023
LumberyardCALIFORNIA12008
SattleyCALIFORNIA12019
RivertonCALIFORNIA12010
Hat CreekCALIFORNIA11998
PaxtonCALIFORNIA12017
Pollock PinesCALIFORNIA12013
Last ChanceCALIFORNIA12019

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