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

Generalists In Iowa

All statesIowa

11 species in this guild. As a group they are -55%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 →

Generalists as a group have fallen sharply in Iowa, down 55% since 1969.

Generalists In Iowa Population Forecast

If the recent trend holds, Generalists in Iowa is projected to fall about 28% by 2030 — from 18 in 2025 to a central estimate of 13 (95% range 0.00–26). A 5-year backtest shows a typical error of ±14.5%, with 100% of held-out values landing inside the 95% band.

-28%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 →
13Projected 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 →
0.00–2695% 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 →
±14.5%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, Generalists in Iowa is projected to fall about 28% by 2030 — from 18 in 2025 to a central estimate of 13 (95% range 0.00–26). A 5-year backtest shows a typical error of ±14.5%, 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 →
2026162.729
2027152.028
2028141.327
2029140.6127
2030130.0026

Member Species In Iowa

Generalists 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 →
House SparrowPasseridae-66%
Rock PigeonColumbidae-53%
Common GrackleIcteridae-45%
American CrowCorvidae-39%
European StarlingSturnidae-24%
Mourning DoveColumbidae-13%
Northern MockingbirdMimidae+41%
Brown-headed CowbirdIcteridae+78%
House FinchFringillidae+291%
Eurasian Tree SparrowPasseridae14×
Eurasian Collared-DoveColumbidae55×

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