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

Grassland Birds In Iowa

All statesIowa

14 species in this guild. As a group they are -65%Guild trendA mean-index aggregate across the species in this group — the structural direction of the guild, with individual-species noise smoothed out.Full methodology → since 1969.

Guild SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

guild collapsecomputed 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 →

Grassland birds as a group have fallen sharply in Iowa, down 65% since 1969.

Forecast

If the recent trend holds, Grassland birds in Iowa is projected to fall about 35% by 2029 — from 6.3 in 2024 to a central estimate of 4.1 (95% range 0.00–9.2). A 5-year backtest shows a typical error of ±38.1%, with 100% of held-out values landing inside the 95% band.

-35%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 →
4.1Projected 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 →
0.00–9.295% 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 →
±38.1%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, Grassland birds in Iowa is projected to fall about 35% by 2029 — from 6.3 in 2024 to a central estimate of 4.1 (95% range 0.00–9.2). A 5-year backtest shows a typical error of ±38.1%, 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 →
20255.10.0010
20264.80.009.9
20274.60.009.7
20284.30.009.4
20294.10.009.2

Member Species In Iowa

Grassland birds species in Iowa.
TrendPercent 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 →
Western MeadowlarkIcteridae-95%
Grasshopper SparrowPasserellidae-94%
Horned LarkAlaudidae-86%
BobolinkIcteridae-76%
Northern BobwhiteOdontophoridae-68%
Vesper SparrowPasserellidae-65%
Savannah SparrowPasserellidae-38%
DickcisselCardinalidae-36%
Ring-necked PheasantPhasianidae-29%
Eastern MeadowlarkIcteridae-27%
Sedge WrenTroglodytidae+173%
Lark SparrowPasserellidae+197%
Upland SandpiperScolopacidae+246%
Henslow's SparrowPasserellidae+293%

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