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

Horned Lark Population Trend in Iowa

All statesGrassland birds

Horned Lark in Iowa has collapsed: down 86% on the route-weighted index since 1969.

-86%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 Horned Lark 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 →

Horned Lark has collapsed in Iowa: down 86% on the route-weighted index since 1969.

Horned Lark Population Forecast in Iowa

If the recent trend holds, Horned Lark in Iowa is projected to fall about 100% by 2029 — from 2.2 in 2024 to a central estimate of 0.00 (95% range 0.00–3.9). A 5-year backtest shows a typical error of ±56%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–3.995% 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 →
±56%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, Horned Lark in Iowa is projected to fall about 100% by 2029 — from 2.2 in 2024 to a central estimate of 0.00 (95% range 0.00–3.9). A 5-year backtest shows a typical error of ±56%, 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 →
20250.980.004.9
20260.720.004.6
20270.460.004.3
20280.200.004.1
20290.000.003.9

Horned Lark Survey Routes in Iowa

Routes recording Horned Lark 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 Valley4719971967
Zearing3019951968
Pierson1620131968
Washta1120131970
Titonka1120011968
Red Rock1020241968
Davis Corner1020241968
Garner819931971
Kanawha420241967
Clare420171967
Tipton420241993
College Spgs319921969
West Liberty320241968
Brooklyn320221967
Williamsburg320221967
Sioux City320231968
Festina320241968
Rock Valley320241968
Bedford220171969
Bryant220241967
Desmoines219741968
Panther220241967
Neola220011968
Prairieburg220191967
Hudson220221967

Horned Lark Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawaregeorgiaidahoillinoisindianakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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