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Species · California · BBS 2025 Release · 1966–2024

Bewick's Wren Population Trend in California

All statesForest birds

Bewick's Wren in California has edged up: up 14% on the route-weighted index since 1970.

+14%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 →
222Routes 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 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 fall about 19% by 2029 — from 5.8 in 2024 to a central estimate of 4.7 (95% range 3.0–6.4). A 5-year backtest shows a typical error of ±19.8%, with 100% of held-out values landing inside the 95% band.

-19%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 →
4.7Projected 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 →
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 →
±19.8%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 fall about 19% by 2029 — from 5.8 in 2024 to a central estimate of 4.7 (95% range 3.0–6.4). A 5-year backtest shows a typical error of ±19.8%, 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 →
20254.73.06.4
20264.73.06.4
20274.73.06.4
20284.73.06.4
20294.73.06.4

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
Elsinore Mtn6620241970
Poway5919801973
Cuyamaca Pk5720241970
Oak Grove4520241968
Iron Gate4420191988
S Catalina4320221988
Jacumba3620241973
South Lake3520062006
Auburn3319801969
Stonyford2820182015
Tres Pinos 22720112005
Anza 22420242005
Mt Baldy2120241970
Hough Springs2120071999
Tres Pinos1920031968
Lake Berryessa1920242023
Colma1819721968
Coyote1820241972
Waterman Gap1820241973
Rumsey1620081969
Silver City1520131972
Lake Cachuma1520161972
Tomhead1520111998
Lockwood Val1420191970

Bewick's Wren Population Trend in Other States

alabamaarizonaarkansascoloradoidahoillinoisindianaiowakansaskentuckymarylandmississippimissourinevadanew-mexiconorth-carolinaohiooklahomaoregonpennsylvaniatennesseetexasutahvirginiawashingtonwest-virginiawisconsinwyoming

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