BirdAnalyst
Species · BCR 15 · BBS 2026 Release · 1966–2025

Brewer's Blackbird In Sierra Nevada

All regionsSierra NevadaGeneralists

Brewer's Blackbird in Sierra Nevada has fallen sharply: down 53% on the route-weighted index since 1970.

-53%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 →
37Routes 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 →
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 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 →

Brewer's Blackbird has fallen sharply in Sierra Nevada: down 53% on the route-weighted index since 1970.

Brewer's Blackbird In Sierra Nevada Population Forecast

If the recent trend holds, Brewer's Blackbird in Sierra Nevada is projected to fall about 33% by 2030 — from 9.1 in 2025 to a central estimate of 6.1 (95% range 0.00–20). A 5-year backtest shows a typical error of ±24.3%, with 100% of held-out values landing inside the 95% band.

-33%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 →
6.1Projected 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 →
0.00–2095% 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 →
±24.3%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, Brewer's Blackbird in Sierra Nevada is projected to fall about 33% by 2030 — from 9.1 in 2025 to a central estimate of 6.1 (95% range 0.00–20). A 5-year backtest shows a typical error of ±24.3%, with 100% 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 →
20267.20.0021
20276.90.0020
20286.70.0020
20296.40.0020
20306.10.0020

Routes In Sierra Nevada

Routes recording Brewer's Blackbird 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 →
SattleyCALIFORNIA652025
WoodfordsCALIFORNIA322025
PaxtonCALIFORNIA302025
KernvilleCALIFORNIA232008
Cottage SpgsCALIFORNIA201975
GoumazCALIFORNIA202011
GeneseeCALIFORNIA182024
Lassen ParkCALIFORNIA121987
Higgins CornCALIFORNIA122025
Hat CreekCALIFORNIA102018
CrestviewCALIFORNIA102025
Little TruckeeCALIFORNIA72025
Butte MeadowCALIFORNIA62014
Last ChanceCALIFORNIA62019
LakeshoreCALIFORNIA52024
Silver CityCALIFORNIA42013
ChilcootCALIFORNIA42024
Eagle LakeCALIFORNIA32024
Bass LakeCALIFORNIA32018
Chaos CraterCALIFORNIA32012
Meadow ValleyCALIFORNIA32025
Greenhorn MtCALIFORNIA22008
DownievilleCALIFORNIA22022
Forest HillCALIFORNIA22001
Pollock PinesCALIFORNIA21999

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