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Species · Michigan · BBS 2025 Release · 1966–2024

Brewer's Blackbird Population Trend in Michigan

All statesGeneralists

Brewer's Blackbird in Michigan has collapsed: down 85% on the route-weighted index since 1969.

-85%Since 1969TrendPercent 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 →
43Routes 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 MichiganNotable 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 collapsed in Michigan: down 85% on the route-weighted index since 1969.

Brewer's Blackbird Population Forecast in Michigan

If the recent trend holds, Brewer's Blackbird in Michigan is projected to rise about 202% by 2029 — from 0.17 in 2024 to a central estimate of 0.51 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±490.5%, with 100% of held-out values landing inside the 95% band.

+202%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 →
0.51Projected 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 →
0.00–1.495% 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 →
±490.5%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 Michigan is projected to rise about 202% by 2029 — from 0.17 in 2024 to a central estimate of 0.51 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±490.5%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.530.001.4
20260.530.001.4
20270.520.001.4
20280.520.001.4
20290.510.001.4

Brewer's Blackbird Survey Routes in Michigan

Routes recording Brewer's Blackbird in Michigan.
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 →
Lake City3820011971
Cathro1019901988
Ned Lake820152015
Herman819971983
Raco819901990
Marenisco719951988
Brocky Lake719871983
Red Oak720071976
Tahquamenon619901976
Pleasant Valley 2620052005
Crystal Fls520171990
Bergland419901982
Ishpeming420231983
New Troy419721972
Pickford420241980
Sand Lake420241983
Mayfield420082000
Seney Nwr320091992
Cunard220151976
Shingleton220041967
Lawrence219911991
Riggsville219931972
Frederic220012001
Oberlin220152000
Harrietta120061993

Brewer's Blackbird Population Trend in Other States

arizonacaliforniacoloradoidahoindianaminnesotamontananebraskanevadanew-mexiconorth-dakotaoklahomaoregonsouth-dakotatexasutahwashingtonwisconsinwyoming

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