BirdAnalyst
Species · California · BBS 2025 Release · 1966–2024

Pygmy Nuthatch Population Trend in California

All statesForest birds

Pygmy Nuthatch in California has fallen sharply: down 65% on the route-weighted index since 1970.

-65%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 →
80Routes In StateSurvey 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 Pygmy Nuthatch Trends in CaliforniaNotable 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 California: down 65% on the route-weighted index since 1970.

Pygmy Nuthatch Population Forecast in California

If the recent trend holds, Pygmy Nuthatch in California is projected to rise about 59% by 2029 — from 0.45 in 2024 to a central estimate of 0.72 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±76.4%, with 100% of held-out values landing inside the 95% band.

+59%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 →
0.72Projected 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 →
0.00–1.795% 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 →
±76.4%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 California is projected to rise about 59% by 2029 — from 0.45 in 2024 to a central estimate of 0.72 (95% range 0.00–1.7). A 5-year backtest shows a typical error of ±76.4%, 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 →
20250.770.001.8
20260.760.001.8
20270.740.001.8
20280.730.001.8
20290.720.001.7

Pygmy Nuthatch Survey Routes in California

Routes recording Pygmy Nuthatch in California.
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 →
Valyermo4520181970
Mt Laguna4119871970
Big Bear3719861969
Mt Pinos1620041969
Lake Hemet1519861970
Fish Rock1020141968
Lake Hemet 2920232013
Pine Mountain820172000
Westville719761976
Lockwood Val619871983
Sattley620191974
Waterman Gap620241972
Hat Creek620181993
Cleveland Nf620181994
Chilcoot620242023
Fairfax520241972
Green Valley520231970
Tehama519921992
Woodlands520242012
Tionesta520211998
Last Chance520191994
Point Reyes420211972
Navarro420111976
Kelso Valley420241975
Anza 2420242005

Pygmy Nuthatch Population Trend in Other States

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