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

Williamson's Sapsucker In Sierra Nevada

All regionsSierra NevadaForest birds

Williamson's Sapsucker in Sierra Nevada has risen sharply: up 65% on the route-weighted index since 1975.

+65%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 →
44YearsYears 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 increasecomputed 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 →

Williamson's Sapsucker has risen sharply in Sierra Nevada: up 65% on the route-weighted index since 1975.

Williamson's Sapsucker In Sierra Nevada Population Forecast

If the recent trend holds, Williamson's Sapsucker in Sierra Nevada is projected to stay roughly flat through 2030, near 0.44 (95% range 0.12–0.77). A 5-year backtest shows a typical error of ±113.2%, with 80% of held-out values landing inside the 95% band.

-0%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 →
0.44Projected 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 →
0.12–0.7795% 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 →
±113.2%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, Williamson's Sapsucker in Sierra Nevada is projected to stay roughly flat through 2030, near 0.44 (95% range 0.12–0.77). A 5-year backtest shows a typical error of ±113.2%, with 80% of held-out values landing inside the 95% band.19722030
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 →
20260.420.100.74
20270.420.100.75
20280.430.110.75
20290.440.110.76
20300.440.120.77

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 →
CrestviewCALIFORNIA52025
LakeshoreCALIFORNIA42004
Eagle LakeCALIFORNIA21985
DardanelleCALIFORNIA22004
Tuolumne GroveCALIFORNIA22014
DownievilleCALIFORNIA21975
GoumazCALIFORNIA22011
Pine MountainCALIFORNIA22017
Lassen ParkCALIFORNIA11976
WoodfordsCALIFORNIA12025
LumberyardCALIFORNIA12025
SattleyCALIFORNIA12019
RivertonCALIFORNIA12010
Hat CreekCALIFORNIA11998
PaxtonCALIFORNIA12017
Little TruckeeCALIFORNIA12025
Pollock PinesCALIFORNIA12013
Last ChanceCALIFORNIA12019

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