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Species · Utah · BBS 2025 Release · 1966–2024

Brewer's Blackbird Population Trend in Utah

All statesGeneralists

Brewer's Blackbird in Utah has fallen sharply: down 57% on the route-weighted index since 1970.

-57%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 →
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 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 57% 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 78% by 2029 — from 6.4 in 2024 to a central estimate of 1.4 (95% range 0.00–20). A 5-year backtest shows a typical error of ±46.5%, with 100% of held-out values landing inside the 95% band.

-78%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 →
1.4Projected 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 →
0.00–2095% 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 →
±46.5%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 78% by 2029 — from 6.4 in 2024 to a central estimate of 1.4 (95% range 0.00–20). A 5-year backtest shows a typical error of ±46.5%, 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 →
20253.20.0022
20262.80.0021
20272.30.0021
20281.90.0020
20291.40.0020

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 →
Kamas12320241997
M Warner Res6420241993
Ant Flat-Ogden Can6020231994
Randolph5720241992
Alton 22820242021
Hardware Ranch2220231994
Dixie Nf2120241993
Bicknell2020211997
Goose Creek Mtn.1820231997
Shivwitz1620141994
Crawford Mts1620172002
Altonah1420151969
Woodruff1420242002
Grouse Creek1220101982
Johnson Can1220241987
E. Bear Lake1220221995
Oak City1120231972
Goshen1120241968
Saleratus Cr1120181995
Wellington 31020242012
Wendover1020111987
Lost Cr. Res1020181996
Leamington920171992
Newcastle920221997
Neponset Res920171995

Brewer's Blackbird Population Trend in Other States

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