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

Pygmy Nuthatch In Sierra Nevada

All regionsSierra NevadaForest birds

Pygmy Nuthatch in Sierra Nevada has fallen sharply: down 72% on the route-weighted index since 1971.

-72%Since 1971TrendPercent 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 →
23Routes 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 →
55YearsYears 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 →

Pygmy Nuthatch has fallen sharply in Sierra Nevada: down 72% on the route-weighted index since 1971.

Forecast

If the recent trend holds, Pygmy Nuthatch in Sierra Nevada is projected to rise about 32% by 2029 — from 0.68 in 2024 to a central estimate of 0.90 (95% range 0.00–2.1). A 5-year backtest shows a typical error of ±120.4%, with 100% of held-out values landing inside the 95% band.

+32%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 →
0.90Projected 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 →
0.00–2.195% 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 →
±120.4%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, Pygmy Nuthatch in Sierra Nevada is projected to rise about 32% by 2029 — from 0.68 in 2024 to a central estimate of 0.90 (95% range 0.00–2.1). A 5-year backtest shows a typical error of ±120.4%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.920.002.1
20260.920.002.1
20270.910.002.1
20280.910.002.1
20290.900.002.1

Routes In Sierra Nevada

Routes recording Pygmy Nuthatch 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 →
Pine MountainCALIFORNIA82017
WestvilleCALIFORNIA71976
SattleyCALIFORNIA62019
Hat CreekCALIFORNIA62018
ChilcootCALIFORNIA62024
Last ChanceCALIFORNIA52019
CrestviewCALIFORNIA42024
WoodfordsCALIFORNIA32024
Greenhorn MtCALIFORNIA32006
Tuolumne GroveCALIFORNIA32021
Chaos CraterCALIFORNIA32001
DardanelleCALIFORNIA22002
PaxtonCALIFORNIA22019
Little TruckeeCALIFORNIA22005
Lassen ParkCALIFORNIA11980
Eagle LakeCALIFORNIA12022
JohnsvilleCALIFORNIA12014
Kings CanyonCALIFORNIA11979
GeneseeCALIFORNIA12023
RivertonCALIFORNIA12008
LakeshoreCALIFORNIA11999
GoumazCALIFORNIA12009
Meadow ValleyCALIFORNIA12014

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