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

House Sparrow Population Trend in Iowa

All statesGeneralists

House Sparrow in Iowa has fallen sharply: down 67% on the route-weighted index since 1969.

-67%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 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 67% 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 77% by 2029 — from 54 in 2024 to a central estimate of 12 (95% range 0.00–84). A 5-year backtest shows a typical error of ±41.2%, with 100% of held-out values landing inside the 95% band.

-77%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 →
12Projected 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 →
0.00–8495% 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 →
±41.2%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, House Sparrow in Iowa is projected to fall about 77% by 2029 — from 54 in 2024 to a central estimate of 12 (95% range 0.00–84). A 5-year backtest shows a typical error of ±41.2%, 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 →
2025250.0097
2026220.0094
2027190.0091
2028160.0087
2029120.0084

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 Valley19220241968
Red Rock11220241968
Maquoketa9520241967
Panther9020241967
Garner9019931971
Desmoines7819791968
Clare7220191967
Bryant6920241967
Gaza6820231969
Lafayette6820242003
Burchinal6420241995
Mccallsburg6420241996
Hudson6320221967
Mt Hamill5920241967
Zearing5719951967
Festina5720241968
Davis Corner5420241968
Alice5319991967
College Spgs5220041967
Sioux City4920241968
Brooklyn4820221967
West Liberty4620241968
Washta4620141967
Bedford4520181968

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 2026-05-22.