BirdAnalyst
Species · BCR 15 · BBS 2025 Release · 1966–2024

Olive-sided Flycatcher In Sierra Nevada

All regionsSierra NevadaAerial insectivores

Olive-sided Flycatcher in Sierra Nevada has collapsed: down 80% on the route-weighted index since 1970.

-80%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 →
38Routes 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 →
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 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 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 collapsed in Sierra Nevada: down 80% on the route-weighted index since 1970.

Olive-sided Flycatcher In Sierra Nevada Population Forecast

If the recent trend holds, Olive-sided Flycatcher in Sierra Nevada is projected to fall about 100% by 2029 — from 4.8 in 2024 to a central estimate of 0.00 (95% range 0.00–6.2). A 5-year backtest shows a typical error of ±86.1%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–6.295% 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 →
±86.1%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 Sierra Nevada is projected to fall about 100% by 2029 — from 4.8 in 2024 to a central estimate of 0.00 (95% range 0.00–6.2). A 5-year backtest shows a typical error of ±86.1%, 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 →
20250.820.007.0
20260.570.006.8
20270.320.006.5
20280.080.006.3
20290.000.006.2

Routes In Sierra Nevada

Routes recording Olive-sided Flycatcher in Sierra Nevada.
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 SpgsCALIFORNIA251975
GeneseeCALIFORNIA232024
Lassen ParkCALIFORNIA201989
Eagle LakeCALIFORNIA172024
Hat CreekCALIFORNIA142018
Tahoe NfCALIFORNIA121994
Last ChanceCALIFORNIA122019
WestvilleCALIFORNIA92024
JohnsvilleCALIFORNIA92024
Pollock PinesCALIFORNIA72024
Pine MountainCALIFORNIA72017
Tuolumne GroveCALIFORNIA62024
RivertonCALIFORNIA62023
LumberyardCALIFORNIA52024
ChilcootCALIFORNIA52024
DardanelleCALIFORNIA42019
Little TruckeeCALIFORNIA42023
Greenhorn MtCALIFORNIA32008
Higgins CornCALIFORNIA32023
LakeshoreCALIFORNIA32024
Chaos CraterCALIFORNIA32019
ChesterCALIFORNIA32017
GoumazCALIFORNIA32011
Forest Hill 2CALIFORNIA32005
DownievilleCALIFORNIA22024

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