BirdAnalyst
Species · BCR 10 · BBS 2025 Release · 1966–2024

Brewer's Blackbird In Northern Rockies

All regionsNorthern RockiesGeneralists

Brewer's Blackbird in Northern Rockies has fallen sharply: down 62% on the route-weighted index since 1970.

-62%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 →
204Routes 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 Northern Rockies: down 62% on the route-weighted index since 1970.

Brewer's Blackbird In Northern Rockies Population Forecast

If the recent trend holds, Brewer's Blackbird in Northern Rockies is projected to fall about 43% by 2029 — from 11 in 2024 to a central estimate of 6.4 (95% range 0.00–14). A 5-year backtest shows a typical error of ±19.2%, with 100% of held-out values landing inside the 95% band.

-43%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 →
6.4Projected 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 →
0.00–1495% 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 →
±19.2%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 Northern Rockies is projected to fall about 43% by 2029 — from 11 in 2024 to a central estimate of 6.4 (95% range 0.00–14). A 5-year backtest shows a typical error of ±19.2%, 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 →
20258.20.7316
20267.70.2915
20277.30.0015
20286.90.0014
20296.40.0014

Routes In Northern Rockies

Routes recording Brewer's Blackbird in Northern Rockies.
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 →
Twin BridgesMONTANA1021976
St MaryMONTANA1002008
BoulderWYOMING982024
SpartaOREGON732001
St. Mary 2MONTANA632024
Fort LoganMONTANA572024
RandolphUTAH572024
RaynesfordMONTANA542024
MeeteetseWYOMING512024
DanielWYOMING511988
WalcottWYOMING512024
Clyde ParkMONTANA502024
PolsonMONTANA492024
Crane CreekIDAHO482019
HarmonyWYOMING462023
CascadeIDAHO451984
AugustaMONTANA452024
Freeman CreekMONTANA422016
BoulderMONTANA412024
Wolf CreekMONTANA412022
AlturasIDAHO381987
Malheur Res.OREGON382023
Green RiverWYOMING381984
ArmintoWYOMING342024
Patrick DrawWYOMING331980

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