BirdAnalyst
Species · California · BBS 2025 Release · 1966–2024

Ash-throated Flycatcher Population Trend in California

All statesAerial insectivores

Ash-throated Flycatcher in California has risen sharply: up 59% on the route-weighted index since 1970.

+59%Since 1970TrendPercent 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 →
219Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Ash-throated Flycatcher 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 →

Ash-throated Flycatcher has risen sharply in California: up 59% on the route-weighted index since 1970.

Ash-throated Flycatcher Population Forecast in California

If the recent trend holds, Ash-throated Flycatcher in California is projected to stay roughly flat through 2029, near 9.2 (95% range 6.6–12). A 5-year backtest shows a typical error of ±5.8%, with 100% 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 →
9.2Projected 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 →
6.6–1295% 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 →
±5.8%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, Ash-throated Flycatcher in California is projected to stay roughly flat through 2029, near 9.2 (95% range 6.6–12). A 5-year backtest shows a typical error of ±5.8%, with 100% 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 →
20259.06.512
20269.16.512
20279.16.612
20289.16.612
20299.26.612

Ash-throated Flycatcher Survey Routes in California

Routes recording Ash-throated Flycatcher 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 →
White River12619921972
Rumsey6720081969
Jackson4919921972
Yokohl Val4719971973
Oneals4520241972
Red Bluff4420241968
Tujunga4420211970
Glamis4220181968
Lake Cachuma3920161972
Folsom3720241984
Sisquoc3720141970
Adelaida3620241970
Tres Pinos 23620112005
Kelso Valley3320241973
Yolla Bolly3320241973
Lake Berryessa3220242023
Elsinore Mtn3220241970
Cal Hot Spgs3220191993
Mt Pinos 23120242005
Iron Gate3120191988
Cuyamaca Pk3020241970
Copperopolis3020241972
Bass Lake2920191972
Jacumba2920241973
Gold Hill2920241972

Ash-throated Flycatcher Population Trend in Other States

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