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

Bald Eagle Population Trend in Iowa

All statesGeneralists

Bald Eagle in Iowa has surged: up 306% on the route-weighted index since 2002.

+306%Since 2002TrendPercent 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 →
17Routes 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 →
20YearsYears 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 IowaNotable 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 Iowa: up 306% on the route-weighted index since 2002.

Bald Eagle Population Forecast in Iowa

If the recent trend holds, Bald Eagle in Iowa is projected to stay roughly flat through 2029, near 0.42 (95% range 0.18–0.65). A 5-year backtest shows a typical error of ±56.8%, with 20% of held-out values landing inside the 95% band.

-8%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 →
0.42Projected 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 →
0.18–0.6595% 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 →
±56.8%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, Bald Eagle in Iowa is projected to stay roughly flat through 2029, near 0.42 (95% range 0.18–0.65). A 5-year backtest shows a typical error of ±56.8%, with 20% of held-out values landing inside the 95% band.20002029
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 →
20250.360.130.59
20260.370.140.61
20270.390.160.62
20280.400.170.64
20290.420.180.65

Bald Eagle Survey Routes in Iowa

Routes recording Bald Eagle in Iowa.
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 →
Melrose420212015
Dinsdale220242024
Festina220242001
Mt Hamill120222011
Exline120242024
Rock Valley120242016
West Liberty120242017
Williamsburg120222022
Red Rock120242012
Panther120242024
Washington120002000
Maquoketa120172000
Prairieburg120192012
Hudson120222006
Kanawha120222022
Mccallsburg120172016
Davis Corner120242015

Bald Eagle Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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