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

MacGillivray's Warbler In Coastal California

All regionsCoastal CaliforniaForest birds

MacGillivray's Warbler in Coastal California has declined: down 42% on the route-weighted index since 1973.

-42%Since 1973TrendPercent 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 →
48YearsYears 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 MacGillivray's Warbler in Coastal California. See the full index history below.

MacGillivray's Warbler In Coastal California Population Forecast

If the recent trend holds, MacGillivray's Warbler in Coastal California is projected to stay roughly flat through 2029, near 0.08 (95% range 0.00–0.18). A 5-year backtest shows a typical error of ±134%, with 100% 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 →
0.08Projected 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 →
0.00–0.1895% 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 →
±134%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, MacGillivray's Warbler in Coastal California is projected to stay roughly flat through 2029, near 0.08 (95% range 0.00–0.18). A 5-year backtest shows a typical error of ±134%, with 100% of held-out values landing inside the 95% band.19712029
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 →
20250.080.000.18
20260.080.000.18
20270.080.000.18
20280.080.000.18
20290.080.000.18

Routes In Coastal California

Routes recording MacGillivray's Warbler 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 →
ValyermoCALIFORNIA42019
LockwoodCALIFORNIA42018
Orange CoveCALIFORNIA21980
Sawmill MtnCALIFORNIA21977
FallsvaleCALIFORNIA21981
Green ValleyCALIFORNIA22013
Red BluffCALIFORNIA11995
CoalingaCALIFORNIA12007
Lake SuccessCALIFORNIA11981
Big BearCALIFORNIA11983
Point ReyesCALIFORNIA11993
CohassetCALIFORNIA12019
FairfaxCALIFORNIA12012
Carmel ValCALIFORNIA12023
SangerCALIFORNIA12024
JacumbaCALIFORNIA11988
White RiverCALIFORNIA11992
TehamaCALIFORNIA12014
Yolla BollyCALIFORNIA12010
Bartlett SpsCALIFORNIA11977
Waterman GapCALIFORNIA12024
Glen EllenCALIFORNIA11979
Glen Ellen 2CALIFORNIA12008
Angelus OaksCALIFORNIA12017
PescaderoCALIFORNIA12018

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