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

Bald Eagle Population Trend in Wisconsin

All statesGeneralists

Bald Eagle in Wisconsin has surged: up 17× on the route-weighted index since 1979.

17×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 →
87Routes 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 →
46YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Bald Eagle 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 →

Bald Eagle has surged in Wisconsin: up 17× on the route-weighted index since 1979.

Bald Eagle Population Forecast in Wisconsin

If the recent trend holds, Bald Eagle in Wisconsin is projected to fall about 27% by 2029 — from 0.64 in 2024 to a central estimate of 0.47 (95% range 0.33–0.61). A 5-year backtest shows a typical error of ±29.7%, with 80% of held-out values landing inside the 95% band.

-27%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 →
0.47Projected 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 →
0.33–0.6195% 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 →
±29.7%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, Bald Eagle in Wisconsin is projected to fall about 27% by 2029 — from 0.64 in 2024 to a central estimate of 0.47 (95% range 0.33–0.61). A 5-year backtest shows a typical error of ±29.7%, with 80% of held-out values landing inside the 95% band.19752029
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 →
20250.430.290.57
20260.440.300.58
20270.450.310.59
20280.460.320.60
20290.470.330.61

Bald Eagle Survey Routes in Wisconsin

Routes recording Bald Eagle 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 →
Cochrane420241989
Omro419961996
Merrill320241992
Mather320231998
Casco320242005
Rolling Grnd320242018
Rhinelander320211999
Hudson220241995
Dresser220241992
Loraine220181984
Gilman220241996
Wausaukee220132013
Washington I220242001
Trempealeau220242003
Wis Rapids220231983
Manawa220161999
New Lisbon220242010
Kendall220232007
Pigeon Creek220242012
Buena Vista220222014
Gresham220242013
Highland220242006
Briggsville220192006
Iron River120242000
Minong120231983

Bald Eagle Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawyoming

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