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

Acorn Woodpecker In Sierra Nevada

All regionsSierra NevadaForest birds

Acorn Woodpecker in Sierra Nevada has fallen sharply: down 68% on the route-weighted index since 1970.

-68%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 →
24Routes 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 →

Acorn Woodpecker has fallen sharply in Sierra Nevada: down 68% on the route-weighted index since 1970.

Acorn Woodpecker In Sierra Nevada Population Forecast

If the recent trend holds, Acorn Woodpecker in Sierra Nevada is projected to stay roughly flat through 2029, near 3.9 (95% range 0.00–11). A 5-year backtest shows a typical error of ±22.5%, with 100% of held-out values landing inside the 95% band.

-1%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 →
3.9Projected 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 →
0.00–1195% 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 →
±22.5%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, Acorn Woodpecker in Sierra Nevada is projected to stay roughly flat through 2029, near 3.9 (95% range 0.00–11). A 5-year backtest shows a typical error of ±22.5%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20254.40.0012
20264.30.0011
20274.10.0011
20284.00.0011
20293.90.0011

Routes In Sierra Nevada

Routes recording Acorn Woodpecker 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 →
Bass LakeCALIFORNIA902019
Greenhorn MtCALIFORNIA602008
Silver CityCALIFORNIA492013
WawonaCALIFORNIA302024
CoultervilleCALIFORNIA242019
Higgins CornCALIFORNIA192024
Cottage SpgsCALIFORNIA141975
Tuolumne GroveCALIFORNIA142024
KernvilleCALIFORNIA122008
Forest HillCALIFORNIA82022
Kings CanyonCALIFORNIA42024
GeneseeCALIFORNIA42024
LakeshoreCALIFORNIA32024
StrawberryCALIFORNIA32019
DownievilleCALIFORNIA22022
Forest Hill 2CALIFORNIA22005
WestvilleCALIFORNIA12022
JohnsvilleCALIFORNIA11996
WoodfordsCALIFORNIA12021
RivertonCALIFORNIA12013
PaxtonCALIFORNIA12024
Meadow ValleyCALIFORNIA12008
PlacervilleCALIFORNIA12021
Pine MountainCALIFORNIA12005

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