BirdAnalyst
Species · Iowa · BBS 2026 Release · 1966–2025

Indigo Bunting Population Trend in Iowa

All statesForest birds

Indigo Bunting in Iowa has surged: up 85% on the route-weighted index since 1969.

+85%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 →
58YearsYears 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 85% 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 15% by 2030 — from 7.9 in 2025 to a central estimate of 6.8 (95% range 4.3–9.2). A 5-year backtest shows a typical error of ±12.3%, with 100% of held-out values landing inside the 95% band.

-15%Change by 2030TrendPercent 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 →
6.8Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
4.3–9.295% 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 →
±12.3%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 15% by 2030 — from 7.9 in 2025 to a central estimate of 6.8 (95% range 4.3–9.2). A 5-year backtest shows a typical error of ±12.3%, with 100% of held-out values landing inside the 95% band.19672030
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 →
20266.64.29.1
20276.74.29.1
20286.74.29.2
20296.74.39.2
20306.84.39.2

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 →
Mt Hamill3120251967
Red Rock2620251968
Festina1920251968
College Spgs 21920252005
Hudson1420251967
Melrose1220251974
Bryant1220251967
Cedar Valley1219971967
Washta1220251970
Exline1120251974
College Spgs1120041967
Wales1120251967
Alice1019991968
Zearing1019951968
Bedford920251968
West Liberty920251968
Titonka920251974
Tipton720251993
Brooklyn620251967
Panther620251967
Mccallsburg620251996
Williamsburg420231967
Washington420251967
Neola420251968
Maquoketa420251969

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 2026-08-14.