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Species · California · BBS 2025 Release · 1966–2024

Hermit Warbler Population Trend in California

All statesForest birds

Hermit Warbler in California has surged: up 446% on the route-weighted index since 1970.

+446%Since 1970
109Routes In State
56Years

Notable Hermit Warbler Trends in California

long arc increasecomputed index

Hermit Warbler has surged in California: up 446% on the route-weighted index since 1970.

Hermit Warbler Population Forecast in California

If the recent trend holds, Hermit Warbler in California is projected to rise about 70% by 2029 — from 2.7 in 2024 to a central estimate of 4.5 (95% range 2.6–6.5). A 5-year backtest shows a typical error of ±63.8%, with 40% of held-out values landing inside the 95% band.

+70%Change by 2029
4.5Projected 2029 index
2.6–6.595% range
±63.8%Backtest error
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 index95% low95% high
20254.32.46.2
20264.42.56.3
20274.42.56.3
20284.52.66.4
20294.52.66.5

Hermit Warbler Survey Routes in California

Routes recording Hermit Warbler in California.
Johnsville6020241975
Lumberyard4820241976
Martins Fy4620091976
Pilot Creek4619961994
Butte Meadow4220141972
Friday Ridge3920241994
Lonesome Rdg3420141994
South Fork Mtn2920222000
Redwood N.P. 22720132012
Riverton2020231974
Placerville1820241998
Downieville1720241976
Hiouchi1420142002
Meadow Valley1120241999
Laytonville1020241974
Westville920241971
Navarro920071976
Alderpoint920121974
Genesee920241973
Carrville819701970
Ship Mtn.820171994
Holmes720241968
Burnt Ranch720161998
Chester720171997
Forest Hill620221997

Hermit Warbler Population Trend in Other States

oregonwashington

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