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

Blue-gray Gnatcatcher In Coastal California

All regionsCoastal CaliforniaForest birds

Blue-gray Gnatcatcher in Coastal California has surged: up 860% on the route-weighted index since 1971.

+860%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 →
73Routes 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 →
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 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 →

Blue-gray Gnatcatcher has surged in Coastal California: up 860% on the route-weighted index since 1971.

Blue-gray Gnatcatcher In Coastal California Population Forecast

If the recent trend holds, Blue-gray Gnatcatcher in Coastal California is projected to stay roughly flat through 2029, near 1.8 (95% range 0.98–2.7). A 5-year backtest shows a typical error of ±52.6%, with 60% of held-out values landing inside the 95% band.

+7%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 →
1.8Projected 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 →
0.98–2.795% 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 →
±52.6%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, Blue-gray Gnatcatcher in Coastal California is projected to stay roughly flat through 2029, near 1.8 (95% range 0.98–2.7). A 5-year backtest shows a typical error of ±52.6%, with 60% 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 →
20251.70.882.6
20261.80.912.6
20271.80.932.7
20281.80.952.7
20291.80.982.7

Routes In Coastal California

Routes recording Blue-gray Gnatcatcher 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 →
Elsinore MtnCALIFORNIA412024
Carmel ValCALIFORNIA172024
Bartlett SpsCALIFORNIA132018
Santa YnezCALIFORNIA102019
Lake CachumaCALIFORNIA102016
StonyfordCALIFORNIA102018
Lake Hemet 2CALIFORNIA92023
RumseyCALIFORNIA82008
Yolla BollyCALIFORNIA62023
CoalingaCALIFORNIA52005
Mt BaldyCALIFORNIA52024
TehamaCALIFORNIA52022
WoodlandsCALIFORNIA52024
Hough SpringsCALIFORNIA52007
Sawmill MtnCALIFORNIA42022
FallsvaleCALIFORNIA41975
TomheadCALIFORNIA42011
ValyermoCALIFORNIA32019
Mt LagunaCALIFORNIA31987
JacksonCALIFORNIA31992
LockwoodCALIFORNIA32024
CalpellaCALIFORNIA21979
San YsidroCALIFORNIA22017
Lake SuccessCALIFORNIA21996
Big BearCALIFORNIA21979

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