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

Indigo Bunting Population Trend in Iowa

All statesGeneralists

Indigo Bunting in Iowa has surged: up 79% on the route-weighted index since 1969.

+79%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 →
39Routes 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 →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Indigo Bunting 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 →

Indigo Bunting has surged in Iowa: up 79% on the route-weighted index since 1969.

Indigo Bunting Population Forecast in Iowa

If the recent trend holds, Indigo Bunting in Iowa is projected to fall about 14% by 2029 — from 7.7 in 2024 to a central estimate of 6.6 (95% range 4.2–9.1). A 5-year backtest shows a typical error of ±9.2%, with 100% of held-out values landing inside the 95% band.

-14%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 →
6.6Projected 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 →
4.2–9.195% 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 →
±9.2%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, Indigo Bunting in Iowa is projected to fall about 14% by 2029 — from 7.7 in 2024 to a central estimate of 6.6 (95% range 4.2–9.1). A 5-year backtest shows a typical error of ±9.2%, 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 →
20256.54.09.0
20266.54.19.0
20276.64.19.0
20286.64.19.0
20296.64.29.1

Indigo Bunting Survey Routes in Iowa

Routes recording Indigo Bunting 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 →
Red Rock5020241968
Mt Hamill1820241967
College Spgs 21720232005
Wales1420181967
Cedar Valley1219971967
Festina1220241968
Exline1120241974
Bedford1120181968
College Spgs1120041967
Alice1019991968
Zearing1019951968
Tipton920241993
Melrose820241974
West Liberty720241968
Panther720241967
Maquoketa720241969
Dinsdale720241968
Bryant620241967
Brooklyn620221967
Mccallsburg620241996
Hudson520221967
Davis Corner520241968
Williamsburg420231967
Clare420191967
Desmoines319791968

Indigo Bunting Population Trend in Other States

alabamaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaillinoisindianakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawest-virginiawisconsinwyoming

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