BirdAnalyst
Species · California · BBS 2026 Release · 1966–2025

Olive-sided Flycatcher Population Trend in California

All statesAerial insectivores

Olive-sided Flycatcher in California has fallen sharply: down 50% on the route-weighted index since 1970.

-50%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 →
158Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Olive-sided 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 declinecomputed 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 →

Olive-sided Flycatcher has fallen sharply in California: down 50% on the route-weighted index since 1970.

Olive-sided Flycatcher Population Forecast in California

If the recent trend holds, Olive-sided Flycatcher in California is projected to stay roughly flat through 2030, near 1.3 (95% range 0.59–2.0). A 5-year backtest shows a typical error of ±24.4%, with 80% of held-out values landing inside the 95% band.

-9%Change by 2030TrendPercent 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 →
1.3Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.59–2.095% 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 →
±24.4%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, Olive-sided Flycatcher in California is projected to stay roughly flat through 2030, near 1.3 (95% range 0.59–2.0). A 5-year backtest shows a typical error of ±24.4%, with 80% of held-out values landing inside the 95% band.19682030
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 →
20261.40.732.2
20271.40.692.1
20281.40.662.1
20291.30.622.1
20301.30.592.0

Olive-sided Flycatcher Survey Routes in California

Routes recording Olive-sided 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 →
Cottage Spgs2519751968
Macdoel2320191972
Genesee2320241972
Waterman Gap2320251972
Lassen Park2019891972
Carrville1619701970
French Gulch1520102002
Hat Creek1420181973
Westville1320251971
Mt Pinos1220041969
Point Reyes1220251970
Valyermo1220191970
Tahoe Nf1219941987
Last Chance1220191993
San Benito Mtn.1120092003
Eagle Lake1020251969
Riverton1020251973
Pilot Creek919961994
Pollock Pines920251997
Mt Pinos 2820242005
Bartle820211972
Hay Fork820172001
Fairfax720241972
Elizabeth Lk719911975
Tuolumne Grove720251972

Olive-sided Flycatcher Population Trend in Other States

alaskaarizonacoloradoidahomainemarylandmassachusettsmichiganminnesotamontananevadanew-hampshirenew-mexiconew-yorknorth-carolinaohiooregonpennsylvaniasouth-dakotautahvermontwashingtonwest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.