BirdAnalyst
Species · California · BBS 2025 Release · 1966–2024

Ruby-crowned Kinglet Population Trend in California

All statesForest birds

Ruby-crowned Kinglet in California has collapsed: down 75% on the route-weighted index since 1970.

-75%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 →
58Routes 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 →
50YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Ruby-crowned Kinglet 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 declinecomputed 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 →

Ruby-crowned Kinglet has collapsed in California: down 75% on the route-weighted index since 1970.

Ruby-crowned Kinglet Population Forecast in California

If the recent trend holds, Ruby-crowned Kinglet in California is projected to stay roughly flat through 2029, near 0.01 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±80%, with 80% of held-out values landing inside the 95% band.

n/aChange 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 →
0.01Projected 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 →
0.00–0.1395% 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 →
±80%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, Ruby-crowned Kinglet in California is projected to stay roughly flat through 2029, near 0.01 (95% range 0.00–0.13). A 5-year backtest shows a typical error of ±80%, 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 →
20250.020.000.14
20260.020.000.14
20270.020.000.14
20280.010.000.14
20290.010.000.13

Ruby-crowned Kinglet Survey Routes in California

Routes recording Ruby-crowned Kinglet 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 →
Korbel919871977
Genesee820191972
Hay Fork720172003
Johnsville620192018
Fallsvale619701970
Navarro519931981
Madeline420021998
Laytonville420011995
Last Chance420192019
Meadow Valley320211999
Lake Success319771974
Hat Creek319911991
Shasta Lake320121981
Lakeshore320041972
Sisquoc320121970
Kings Canyon219851985
Calpella219681968
Cottage Spgs219681968
Dardanelle220061973
Bass Lake219811977
Likely219731973
Jackson219721972
Foster Park219741974
Orange Cove219771977
Tahoe Nf219931993

Ruby-crowned Kinglet Population Trend in Other States

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