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

House Sparrow Population Trend in Iowa

All statesGeneralists

House Sparrow in Iowa has fallen sharply: down 66% on the route-weighted index since 1969.

-66%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 House 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 →

long arc declinecomputed 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 →

House Sparrow has fallen sharply in Iowa: down 66% on the route-weighted index since 1969.

House Sparrow Population Forecast in Iowa

If the recent trend holds, House Sparrow in Iowa is projected to fall about 79% by 2030 — from 53 in 2025 to a central estimate of 11 (95% range 0.00–83). A 5-year backtest shows a typical error of ±49%, with 100% of held-out values landing inside the 95% band.

-79%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 →
11Projected 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 →
0.00–8395% 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 →
±49%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, House Sparrow in Iowa is projected to fall about 79% by 2030 — from 53 in 2025 to a central estimate of 11 (95% range 0.00–83). A 5-year backtest shows a typical error of ±49%, 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 →
2026240.0096
2027210.0092
2028180.0089
2029140.0086
2030110.0083

House Sparrow Survey Routes in Iowa

Routes recording House 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 →
Cedar Valley26419971967
Rock Valley17020251968
Red Rock14720251968
West Liberty13320251968
Festina11920251968
Bryant10520251967
Garner9019931971
Panther8920251967
Desmoines7819791968
Pierson7820251968
Clare7220191967
Maquoketa6920251967
Lafayette6820252003
Zearing5719951967
Burchinal5520251995
Alice5319991967
College Spgs5220041967
Hudson5220251967
Washington4820251967
Neola4820251968
Mccallsburg4820251996
Prairieburg4620251967
Tipton3620251993
Williamsburg3320231967
Davis Corner3220251968

House Sparrow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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