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

Grassland Birds In Iowa

All statesIowa

13 species in this guild. As a group they are -68%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 68% since 1969.

Grassland Birds In Iowa Population Forecast

If the recent trend holds, Grassland birds in Iowa is projected to fall about 48% by 2030 — from 6.7 in 2025 to a central estimate of 3.5 (95% range 0.00–8.5). A 5-year backtest shows a typical error of ±41.7%, with 100% of held-out values landing inside the 95% band.

-48%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 →
3.5Projected 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 →
0.00–8.595% 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 →
±41.7%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 48% by 2030 — from 6.7 in 2025 to a central estimate of 3.5 (95% range 0.00–8.5). A 5-year backtest shows a typical error of ±41.7%, 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 →
20264.30.009.4
20274.10.009.2
20283.90.009.0
20293.70.008.8
20303.50.008.5

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-87%
Loggerhead ShrikeLaniidae-86%
BobolinkIcteridae-82%
Vesper SparrowPasserellidae-66%
DickcisselCardinalidae-41%
Eastern MeadowlarkIcteridae-27%
Savannah SparrowPasserellidae-3%
Lark SparrowPasserellidae+160%
Sedge WrenTroglodytidae+187%
Henslow's SparrowPasserellidae+204%
Upland SandpiperScolopacidae+280%

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