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

Grassland Birds In Delaware

All statesDelaware

6 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 1968.

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 Delaware, down 65% since 1968.

Grassland Birds In Delaware Population Forecast

If the recent trend holds, Grassland birds in Delaware is projected to fall about 78% by 2029 — from 3.6 in 2024 to a central estimate of 0.78 (95% range 0.00–3.7). A 5-year backtest shows a typical error of ±74.4%, with 20% of held-out values landing inside the 95% band.

-78%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 →
0.78Projected 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 →
0.00–3.795% 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 →
±74.4%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 Delaware is projected to fall about 78% by 2029 — from 3.6 in 2024 to a central estimate of 0.78 (95% range 0.00–3.7). A 5-year backtest shows a typical error of ±74.4%, with 20% of held-out values landing inside the 95% band.19662029
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 →
20251.40.004.3
20261.30.004.2
20271.10.004.0
20280.940.003.8
20290.780.003.7

Member Species In Delaware

Grassland birds species in Delaware.
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 →
Northern BobwhiteOdontophoridae-95%
Eastern MeadowlarkIcteridae-94%
Vesper SparrowPasserellidae-81%
Ring-necked PheasantPhasianidae-64%
Horned LarkAlaudidae+46%
Grasshopper SparrowPasserellidae+129%

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