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Species · Montana · BBS 2025 Release · 1966–2024

Black-billed Cuckoo Population Trend in Montana

All statesGeneralists

Black-billed Cuckoo in Montana has fallen sharply: down 71% on the route-weighted index since 1971.

-71%Since 1971TrendPercent 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 →
29Routes 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 →
37YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Black-billed Cuckoo Trends in MontanaNotable 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 →

Black-billed Cuckoo has fallen sharply in Montana: down 71% on the route-weighted index since 1971.

Black-billed Cuckoo Population Forecast in Montana

If the recent trend holds, Black-billed Cuckoo in Montana is projected to fall about 100% by 2028 — from 0.08 in 2023 to a central estimate of 0.00 (95% range 0.00–0.23). A 5-year backtest shows a typical error of ±246.8%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2028TrendPercent 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 →
0.00Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.2395% 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 →
±246.8%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, Black-billed Cuckoo in Montana is projected to fall about 100% by 2028 — from 0.08 in 2023 to a central estimate of 0.00 (95% range 0.00–0.23). A 5-year backtest shows a typical error of ±246.8%, with 100% of held-out values landing inside the 95% band.19682028
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 →
20240.000.000.23
20250.000.000.23
20260.000.000.23
20270.000.000.23
20280.000.000.23

Black-billed Cuckoo Survey Routes in Montana

Routes recording Black-billed Cuckoo in Montana.
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 →
Brandenberg819811969
Chuffey Spring620232023
Savage319781978
Willow Creek 2220141983
St Mary119891989
Cleveland119831983
Harlem119801980
Glasgow120001989
Oswego120122012
Bull Mtn.119951995
Augusta119811977
Highwood120121989
Jordan119941994
Circle120021979
Flatwillow119891968
Ingomar119781968
Forsyth119911989
Locate120081984
Webster119891979
Twin Bridges119761968
Willow Creek119781973
Chestnut119891968
Reed Point119921977
Laurel119971975
St Xavier119941982

Black-billed Cuckoo Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawaregeorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

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