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Species · California · BBS 2026 Release · 1966–2025

Bewick's Wren Population Trend in California

All statesForest birds

Bewick's Wren in California has edged up: up 16% on the route-weighted index since 1970.

+16%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 →
223Routes 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 Bewick's 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 →

No notable trend signals for Bewick's Wren in California. See the full index history below.

Bewick's Wren Population Forecast in California

If the recent trend holds, Bewick's Wren in California is projected to stay roughly flat through 2030, near 4.7 (95% range 3.0–6.4). A 5-year backtest shows a typical error of ±19.2%, with 100% of held-out values landing inside the 95% band.

+5%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 →
4.7Projected 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 →
3.0–6.495% 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 →
±19.2%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, Bewick's Wren in California is projected to stay roughly flat through 2030, near 4.7 (95% range 3.0–6.4). A 5-year backtest shows a typical error of ±19.2%, with 100% 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 →
20264.73.06.4
20274.73.06.4
20284.73.06.4
20294.73.06.4
20304.73.06.4

Bewick's Wren Survey Routes in California

Routes recording Bewick's 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 →
Santa Cruz I7719881988
Poway5919801973
S Catalina5020251988
Iron Gate4420191988
South Lake3520062006
Auburn3319801969
Cuyamaca Pk3120251970
Stonyford2820182015
Waterman Gap2720251973
Tres Pinos 22720112005
Mt Baldy2120241970
Hough Springs2120071999
Tres Pinos1920031968
Colma1819721968
Rumsey1620081969
Point Reyes1620251970
Jacumba1620251973
Lake Berryessa1520252023
Silver City1520131972
Lake Cachuma1520161972
Tomhead1520111998
Lockwood Val1420191970
Elsinore Mtn1420251970
Coyote1420251972
Elizabeth Lk1320161972

Bewick's Wren Population Trend in Other States

alabamaarizonaarkansascoloradoidahoillinoisindianaiowakansaskentuckymarylandmississippimissourinevadanew-mexiconorth-carolinaohiooklahomaoregonpennsylvaniatennesseetexasutahvirginiawashingtonwest-virginiawisconsinwyoming

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