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

Brewer's Blackbird Population Trend in Utah

All statesGeneralists

Brewer's Blackbird in Utah has fallen sharply: down 59% on the route-weighted index since 1970.

-59%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 →
94Routes 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 Brewer's Blackbird Trends in UtahNotable 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 Utah: down 59% on the route-weighted index since 1970.

Brewer's Blackbird Population Forecast in Utah

If the recent trend holds, Brewer's Blackbird in Utah is projected to fall about 75% by 2030 — from 4.7 in 2025 to a central estimate of 1.2 (95% range 0.00–19). A 5-year backtest shows a typical error of ±45.7%, with 100% of held-out values landing inside the 95% band.

-75%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 →
1.2Projected 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 →
0.00–1995% 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 →
±45.7%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 Utah is projected to fall about 75% by 2030 — from 4.7 in 2025 to a central estimate of 1.2 (95% range 0.00–19). A 5-year backtest shows a typical error of ±45.7%, 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 →
20262.90.0021
20272.50.0021
20282.00.0020
20291.60.0020
20301.20.0019

Brewer's Blackbird Survey Routes in Utah

Routes recording Brewer's Blackbird in Utah.
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 →
Kamas8320251997
Ant Flat-Ogden Can3920251994
M Warner Res2720251993
Alton 22420252021
Randolph2220251992
Hardware Ranch2220231994
Woodruff1820252002
Shivwitz1620141994
Crawford Mts1620172002
Altonah1420151969
Grouse Creek1220101982
Johnson Can1220241987
Promontory1120251969
Oak City1120231972
Goose Creek Mtn.1120251997
Saleratus Cr1120181995
Wellington 31020242012
Wendover1020111987
Lynn1020251982
Lost Cr. Res1020181996
Vernon920251992
Leamington920171992
Neponset Res920171995
Fairfield820241987
Alton820181997

Brewer's Blackbird Population Trend in Other States

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