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

Brewer's Blackbird In Sierra Nevada

All regionsSierra NevadaGeneralists

Brewer's Blackbird in Sierra Nevada has fallen sharply: down 55% on the route-weighted index since 1970.

-55%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 →
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 →

Brewer's Blackbird has fallen sharply in Sierra Nevada: down 55% 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 51% by 2029 — from 13 in 2024 to a central estimate of 6.3 (95% range 0.00–20). A 5-year backtest shows a typical error of ±22.6%, with 100% of held-out values landing inside the 95% band.

-51%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 →
6.3Projected 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 →
0.00–2095% 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 →
±22.6%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, Brewer's Blackbird in Sierra Nevada is projected to fall about 51% by 2029 — from 13 in 2024 to a central estimate of 6.3 (95% range 0.00–20). A 5-year backtest shows a typical error of ±22.6%, 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 →
20257.40.0021
20267.10.0021
20276.80.0020
20286.50.0020
20296.30.0020

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 →
SattleyCALIFORNIA1432024
WoodfordsCALIFORNIA332024
KernvilleCALIFORNIA232008
Cottage SpgsCALIFORNIA201975
GoumazCALIFORNIA202011
Little TruckeeCALIFORNIA192023
GeneseeCALIFORNIA182024
PaxtonCALIFORNIA152024
Lassen ParkCALIFORNIA121987
Hat CreekCALIFORNIA102018
Butte MeadowCALIFORNIA62014
Last ChanceCALIFORNIA62019
JohnsvilleCALIFORNIA52019
LakeshoreCALIFORNIA52024
Meadow ValleyCALIFORNIA52024
CrestviewCALIFORNIA52024
Silver CityCALIFORNIA42013
Tuolumne GroveCALIFORNIA42024
ChilcootCALIFORNIA42024
Eagle LakeCALIFORNIA32024
Bass LakeCALIFORNIA32018
Higgins CornCALIFORNIA32024
Chaos CraterCALIFORNIA32012
Greenhorn MtCALIFORNIA22008
DownievilleCALIFORNIA22022

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