BirdAnalyst
Species · Montana · BBS 2025 Release · 1966–2024

Bufflehead Population Trend in Montana

All statesWaterfowl

Bufflehead in Montana has surged: up 252% on the route-weighted index since 1979.

+252%Since 1979TrendPercent 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 →
16Routes 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 →
30YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Bufflehead 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 increasecomputed 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 →

Bufflehead has surged in Montana: up 252% on the route-weighted index since 1979.

Bufflehead Population Forecast in Montana

If the recent trend holds, Bufflehead in Montana is projected to fall about 41% by 2029 — from 0.23 in 2024 to a central estimate of 0.14 (95% range 0.00–0.33). A 5-year backtest shows a typical error of ±81.9%, with 60% of held-out values landing inside the 95% band.

-41%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 →
0.14Projected 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 →
0.00–0.3395% 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 →
±81.9%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, Bufflehead in Montana is projected to fall about 41% by 2029 — from 0.23 in 2024 to a central estimate of 0.14 (95% range 0.00–0.33). A 5-year backtest shows a typical error of ±81.9%, with 60% of held-out values landing inside the 95% band.19742029
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 →
20250.130.000.33
20260.130.000.33
20270.130.000.33
20280.140.000.33
20290.140.000.33

Bufflehead Survey Routes in Montana

Routes recording Bufflehead 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 →
Hebgen Lake1620242017
Virgelle520232023
Red Rock419951995
Shawmut419951979
Westby320192019
St Mary220081987
Sunburst219961996
St. Mary 2220242009
East Glacier Park220242024
Wise River220072007
Two Dot220012000
Dinosaurs H.M.220192019
Inside Road120052005
Kalispell120121974
Clancy120232015
Augusta120221991

Bufflehead Population Trend in Other States

alaskacaliforniacoloradoidahominnesotanevadanorth-dakotaoregonsouth-dakotautahwashingtonwisconsinwyoming

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