BirdAnalyst
Species · BCR 32 · BBS 2025 Release · 1966–2024

Cassin's Kingbird In Coastal California

All regionsCoastal CaliforniaAerial insectivores

Cassin's Kingbird in Coastal California has surged: up 268% on the route-weighted index since 1971.

+268%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 →
36Routes 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 →
54YearsYears 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 →

Cassin's Kingbird has surged in Coastal California: up 268% on the route-weighted index since 1971.

Cassin's Kingbird In Coastal California Population Forecast

If the recent trend holds, Cassin's Kingbird in Coastal California is projected to fall about 59% by 2029 — from 2.1 in 2024 to a central estimate of 0.86 (95% range 0.20–1.5). A 5-year backtest shows a typical error of ±48.1%, with 40% of held-out values landing inside the 95% band.

-59%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 →
0.86Projected 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 →
0.20–1.595% 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 →
±48.1%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 Coastal California is projected to fall about 59% by 2029 — from 2.1 in 2024 to a central estimate of 0.86 (95% range 0.20–1.5). A 5-year backtest shows a typical error of ±48.1%, 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 →
20250.800.151.5
20260.820.161.5
20270.830.171.5
20280.850.191.5
20290.860.201.5

Routes In Coastal California

Routes recording Cassin's Kingbird in Coastal 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 →
MorenoCALIFORNIA262024
Oak GroveCALIFORNIA182024
Jofegan 2CALIFORNIA172024
Elsinore MtnCALIFORNIA112024
Hollister 2CALIFORNIA112024
San YsidroCALIFORNIA102019
Elizabeth LkCALIFORNIA92016
CrestonCALIFORNIA81983
Santa YnezCALIFORNIA62019
AnzaCALIFORNIA61981
Harbor Lake 2CALIFORNIA62024
Cp. PendletonCALIFORNIA52004
Foster ParkCALIFORNIA41981
Mt PinosCALIFORNIA41969
SisquocCALIFORNIA42014
JacumbaCALIFORNIA42024
WoodlandsCALIFORNIA32016
Tres PinosCALIFORNIA21977
Mesa GrandeCALIFORNIA22024
Cuyamaca PkCALIFORNIA22023
AdelaidaCALIFORNIA22024
Green ValleyCALIFORNIA22016
LockwoodCALIFORNIA22004
JofeganCALIFORNIA22023
ParkfieldCALIFORNIA12014

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