BirdAnalyst
Species · California · BBS 2026 Release · 1966–2025

Rock Wren Population Trend in California

All statesForest birds

Rock Wren in California has risen sharply: up 75% on the route-weighted index since 1970.

+75%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 →
164Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Rock Wren 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 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 →

Rock Wren has risen sharply in California: up 75% on the route-weighted index since 1970.

Rock Wren Population Forecast in California

If the recent trend holds, Rock Wren in California is projected to stay roughly flat through 2030, near 1.2 (95% range 0.18–2.2). A 5-year backtest shows a typical error of ±70.1%, with 80% of held-out values landing inside the 95% band.

-3%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 →
1.2Projected 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 →
0.18–2.295% 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 →
±70.1%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, Rock Wren in California is projected to stay roughly flat through 2030, near 1.2 (95% range 0.18–2.2). A 5-year backtest shows a typical error of ±70.1%, with 80% of held-out values landing inside the 95% band.19682030
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 →
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Rock Wren Survey Routes in California

Routes recording Rock Wren 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 →
Dorris2420191972
Lake Hemet 22419941993
Ingalls2020251973
Eagle Lake1620251969
Bodie1520251986
Pine Mountain1120171997
White River1019921972
Big Pine920251968
Kelso Valley920241973
Barstow819981968
Chilcoot820241998
Onyx720151968
Woodfords720251976
Honey Lake720251973
Hat Creek620181998
Wildrose520221977
Iron Gate520191988
Pennington419761976
Moreno420241973
Ravendale420251974
Benton420241975
Valyermo420191970
Elizabeth Lk420151970
Greenwater V420241977
Bartle420211974

Rock Wren Population Trend in Other States

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