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Species · California · BBS 2025 Release · 1966–2024

Cassin's Kingbird Population Trend in California

All statesAerial insectivores

Cassin's Kingbird in California has surged: up 223% on the route-weighted index since 1971.

+223%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 →
49Routes 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 →
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 Cassin's Kingbird 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 →

Cassin's Kingbird has surged in California: up 223% on the route-weighted index since 1971.

Cassin's Kingbird Population Forecast in California

If the recent trend holds, Cassin's Kingbird in California is projected to fall about 66% by 2029 — from 1.1 in 2024 to a central estimate of 0.37 (95% range 0.02–0.71). A 5-year backtest shows a typical error of ±60.4%, with 40% of held-out values landing inside the 95% band.

-66%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 →
0.37Projected 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 →
0.02–0.7195% 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 →
±60.4%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, Cassin's Kingbird in California is projected to fall about 66% by 2029 — from 1.1 in 2024 to a central estimate of 0.37 (95% range 0.02–0.71). A 5-year backtest shows a typical error of ±60.4%, with 40% of held-out values landing inside the 95% band.19692029
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 →
20250.350.000.69
20260.350.010.70
20270.360.010.70
20280.360.020.71
20290.370.020.71

Cassin's Kingbird Survey Routes in California

Routes recording Cassin's Kingbird 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 →
Moreno2620241982
Oak Grove1820241969
Jofegan 21720242024
Elsinore Mtn1120241995
Hollister 21120242016
San Ysidro1020191986
Elizabeth Lk920161979
Creston819831982
Imperial Dam820061976
Lenwood719801980
Santa Ynez620191969
Harbor Lake 2620242014
Anza619811972
Cp. Pendleton520041972
Jacumba420241973
Foster Park419811970
Mt Pinos419691969
Cima419981975
Sisquoc420141981
Cottonwood319891989
Woodlands320162012
Green Valley220162013
Tres Pinos219771977
Lockwood220041972
Jofegan220232006

Cassin's Kingbird Population Trend in Other States

arizonacoloradokansasmontananebraskanevadanew-mexicooklahomasouth-dakotatexasutahwyoming

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