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

Osprey Population Trend in Wisconsin

All statesGeneralists

Osprey in Wisconsin has surged: up 359% on the route-weighted index since 1969.

+359%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 →
54Routes 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 WisconsinNotable 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 Wisconsin: up 359% on the route-weighted index since 1969.

Osprey Population Forecast in Wisconsin

If the recent trend holds, Osprey in Wisconsin is projected to fall about 18% by 2029 — from 0.22 in 2024 to a central estimate of 0.18 (95% range 0.10–0.26). A 5-year backtest shows a typical error of ±31%, with 100% of held-out values landing inside the 95% band.

-18%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 →
0.18Projected 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 →
0.10–0.2695% 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 →
±31%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 Wisconsin is projected to fall about 18% by 2029 — from 0.22 in 2024 to a central estimate of 0.18 (95% range 0.10–0.26). A 5-year backtest shows a typical error of ±31%, 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 →
20250.170.090.25
20260.170.090.26
20270.180.090.26
20280.180.100.26
20290.180.100.26

Osprey Survey Routes in Wisconsin

Routes recording Osprey in Wisconsin.
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 →
Omro 2920242002
Gilman319921992
Cumberland220231989
Couderay220191977
Omro220011997
Manitowoc220242007
Flambeau220231998
Beaver Dam220132011
Minong120211979
Grand View120062006
Bayfield120001999
Shanagolden120161983
Montreal120192007
Land O Lakes120161988
Hudson120232007
Dresser120221990
Union Twp120101984
Loraine120181969
Weyerhauser120241973
Exeland120112011
Phillips120242009
Rib Lake120241988
Merrill119761976
Irma120121968
Mcnaughton120241988

Osprey Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawyoming

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