BirdAnalyst
Species · BCR 15 · BBS 2025 Release · 1966–2024

Hermit Warbler In Sierra Nevada

All regionsSierra NevadaForest birds

Hermit Warbler in Sierra Nevada has surged: up 109% on the route-weighted index since 1971.

+109%Since 1971TrendPercent 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 →
38Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 →

Hermit Warbler has surged in Sierra Nevada: up 109% on the route-weighted index since 1971.

Hermit Warbler In Sierra Nevada Population Forecast

If the recent trend holds, Hermit Warbler in Sierra Nevada is projected to stay roughly flat through 2029, near 10 (95% range 5.9–14). A 5-year backtest shows a typical error of ±16.3%, with 80% of held-out values landing inside the 95% band.

+4%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 →
10Projected 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 →
5.9–1495% 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 →
±16.3%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, Hermit Warbler in Sierra Nevada is projected to stay roughly flat through 2029, near 10 (95% range 5.9–14). A 5-year backtest shows a typical error of ±16.3%, with 80% 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 →
20259.95.714
2026105.714
2027105.814
2028105.914
2029105.914

Routes In Sierra Nevada

Routes recording Hermit Warbler in Sierra Nevada.
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 →
JohnsvilleCALIFORNIA602024
LumberyardCALIFORNIA482024
Butte MeadowCALIFORNIA422014
RivertonCALIFORNIA202023
PlacervilleCALIFORNIA182024
DownievilleCALIFORNIA172024
Meadow ValleyCALIFORNIA112024
WestvilleCALIFORNIA92024
GeneseeCALIFORNIA92024
ChesterCALIFORNIA72017
Forest HillCALIFORNIA62022
StrawberryCALIFORNIA62019
Cottage SpgsCALIFORNIA51975
Bass LakeCALIFORNIA51980
Silver CityCALIFORNIA52013
Forest Hill 2CALIFORNIA52005
Tuolumne GroveCALIFORNIA42024
Tahoe NfCALIFORNIA41994
GoumazCALIFORNIA42009
Pollock PinesCALIFORNIA42024
DardanelleCALIFORNIA32019
Hat CreekCALIFORNIA32018
WawonaCALIFORNIA32024
ChilcootCALIFORNIA32023
Lassen ParkCALIFORNIA21987

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