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

Purple Martin In Coastal California

All regionsCoastal CaliforniaAerial insectivores

Purple Martin in Coastal California has edged up: up 14% on the route-weighted index since 1971.

+14%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 →
29Routes 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 →
53YearsYears 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 →

No notable trend signals for Purple Martin in Coastal California. See the full index history below.

Forecast

If the recent trend holds, Purple Martin in Coastal California is projected to fall about 48% by 2029 — from 0.34 in 2024 to a central estimate of 0.18 (95% range 0.00–0.38). A 5-year backtest shows a typical error of ±37.5%, with 80% of held-out values landing inside the 95% band.

-48%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 →
0.18Projected 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 →
0.00–0.3895% 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 →
±37.5%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, Purple Martin in Coastal California is projected to fall about 48% by 2029 — from 0.34 in 2024 to a central estimate of 0.18 (95% range 0.00–0.38). A 5-year backtest shows a typical error of ±37.5%, 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 →
20250.170.000.38
20260.170.000.38
20270.170.000.38
20280.170.000.38
20290.180.000.38

Routes In Coastal California

Routes recording Purple Martin 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 →
Glen EllenCALIFORNIA81997
CrestonCALIFORNIA72024
Point ReyesCALIFORNIA52023
Santa YnezCALIFORNIA42002
FairfaxCALIFORNIA42024
Waterman GapCALIFORNIA42024
Carmel ValCALIFORNIA32023
Mt LagunaCALIFORNIA31974
GreenfieldCALIFORNIA32021
Cleveland Nf 2CALIFORNIA32022
Tres PinosCALIFORNIA21981
ParkfieldCALIFORNIA21968
El ToroCALIFORNIA21980
Lake HemetCALIFORNIA21981
Bartlett SpsCALIFORNIA22018
Cleveland NfCALIFORNIA22013
PescaderoCALIFORNIA22022
AlamarCALIFORNIA22014
MorenoCALIFORNIA12021
Oak GroveCALIFORNIA11970
Lockwood ValCALIFORNIA11984
Cp. PendletonCALIFORNIA11978
Cuyamaca PkCALIFORNIA12003
AdelaidaCALIFORNIA11972
ReddingCALIFORNIA11977

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