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Species · California · BBS 2025 Release · 1966–2024

Pacific Wren Population Trend in California

All statesForest birds

Pacific Wren in California has surged: up 353% on the route-weighted index since 1970.

+353%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 →
63Routes 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 Pacific 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 →

Pacific Wren has surged in California: up 353% on the route-weighted index since 1970.

Pacific Wren Population Forecast in California

If the recent trend holds, Pacific Wren in California is projected to rise about 41% by 2029 — from 0.89 in 2024 to a central estimate of 1.3 (95% range 0.63–1.9). A 5-year backtest shows a typical error of ±95.5%, with 40% of held-out values landing inside the 95% band.

+41%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 →
1.3Projected 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 →
0.63–1.995% 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 →
±95.5%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, Pacific Wren in California is projected to rise about 41% by 2029 — from 0.89 in 2024 to a central estimate of 1.3 (95% range 0.63–1.9). A 5-year backtest shows a typical error of ±95.5%, with 40% 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 →
20251.20.561.8
20261.20.581.8
20271.20.601.9
20281.20.611.9
20291.30.631.9

Pacific Wren Survey Routes in California

Routes recording Pacific 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 →
Redwood N.P. 27620132012
Redwood N.P.4220101995
Pescadero2820241992
Point Reyes1220231975
Waterman Gap1120241972
Holmes1020241968
Crescent Cty920241972
Bartle819741974
Rio Dell720121972
Navarro620111976
Hiouchi520142002
Big Flat520142002
Whiskeytown420072007
Laytonville420241972
Lumberyard420242002
Honeydew320171975
Ship Mtn.320171994
Westville320241974
Tuolumne Grove320181972
Placerville320241997
Offield Mtn320131973
Hay Fork320162002
Pilot Creek219941994
Fish Rock220141975
Friday Ridge220241998

Pacific Wren Population Trend in Other States

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