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

Field Sparrow Population Trend in Iowa

All statesForest birds

Field Sparrow in Iowa has declined: down 42% on the route-weighted index since 1969.

-42%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 →
38Routes 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 Field Sparrow 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 →

No notable trend signals for Field Sparrow in Iowa. See the full index history below.

Field Sparrow Population Forecast in Iowa

If the recent trend holds, Field Sparrow in Iowa is projected to stay roughly flat through 2030, near 3.2 (95% range 1.1–5.3). A 5-year backtest shows a typical error of ±59.8%, with 100% of held-out values landing inside the 95% band.

-4%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 →
3.2Projected 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 →
1.1–5.395% 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 →
±59.8%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, Field Sparrow in Iowa is projected to stay roughly flat through 2030, near 3.2 (95% range 1.1–5.3). A 5-year backtest shows a typical error of ±59.8%, 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 →
20263.31.25.4
20273.31.25.4
20283.31.25.4
20293.31.15.4
20303.21.15.3

Field Sparrow Survey Routes in Iowa

Routes recording Field Sparrow 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 →
Wales1620251967
Washta1320251967
College Spgs 21220252005
Maquoketa1120251967
Exline920251974
Bryant720251967
Mt Hamill620251967
Bedford620251968
Williamsburg620231967
Neola520251968
Hudson420251967
Garner419921973
Tipton420251993
West Liberty320251968
Alice319991967
Pierson320251987
Melrose220251974
College Spgs220041967
Sioux City220191968
Festina220251968
Davis Corner220241971
Cedar Valley119971967
Brooklyn120251967
Red Rock120241968
Desmoines119791968

Field Sparrow Population Trend in Other States

alabamaarkansascoloradoconnecticutdelawarefloridageorgiaillinoisindianakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanew-hampshirenew-jerseynew-yorknorth-carolinanorth-dakotaohiooklahomapennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasvermontvirginiawest-virginiawisconsinwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.