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

Osprey Population Trend in Montana

All statesGeneralists

Osprey in Montana has surged: up 193% on the route-weighted index since 1971.

+193%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 →
42Routes 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 →
54YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Osprey 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 →

Osprey has surged in Montana: up 193% on the route-weighted index since 1971.

Osprey Population Forecast in Montana

If the recent trend holds, Osprey in Montana is projected to rise about 49% by 2029 — from 0.20 in 2024 to a central estimate of 0.30 (95% range 0.14–0.46). A 5-year backtest shows a typical error of ±48.6%, with 100% of held-out values landing inside the 95% band.

+49%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 →
0.30Projected 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 →
0.14–0.4695% 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 →
±48.6%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, Osprey in Montana is projected to rise about 49% by 2029 — from 0.20 in 2024 to a central estimate of 0.30 (95% range 0.14–0.46). A 5-year backtest shows a typical error of ±48.6%, 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 →
20250.290.130.45
20260.290.130.45
20270.290.130.45
20280.290.140.45
20290.300.140.46

Osprey Survey Routes in Montana

Routes recording Osprey 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 →
Jordan420241983
Clinton320241989
Reed Point320171998
Libby Dam220121984
St Mary220071970
Victor220192019
Hebgen Lake220242017
St. Mary 2220242009
Kalispell120241968
Logan Pass119891989
Cleveland120022000
Glen120242002
Willow Creek 2120241988
St Regis120172017
Arlee120221979
Augusta120212021
Woodman120182012
Elliston120172005
Boulder119781978
Inside Road120082003
Forsyth120152013
Sula120192014
Chestnut120182018
Laurel120212011
St Xavier120102006

Osprey Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourinebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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