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

Grassland Birds In Vermont

All statesVermont

7 species in this guild. As a group they are -62%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 Vermont, down 62% since 1968.

Grassland Birds In Vermont Population Forecast

If the recent trend holds, Grassland birds in Vermont is projected to fall about 41% by 2029 — from 2.4 in 2024 to a central estimate of 1.4 (95% range 0.00–3.3). A 5-year backtest shows a typical error of ±35.8%, with 100% of held-out values landing inside the 95% band.

-41%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 →
1.4Projected 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 →
0.00–3.395% 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 →
±35.8%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 Vermont is projected to fall about 41% by 2029 — from 2.4 in 2024 to a central estimate of 1.4 (95% range 0.00–3.3). A 5-year backtest shows a typical error of ±35.8%, with 100% 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 →
20251.70.003.5
20261.60.003.5
20271.50.003.4
20281.50.003.3
20291.40.003.3

Member Species In Vermont

Grassland birds species in Vermont.
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 →
Eastern MeadowlarkIcteridae-96%
Vesper SparrowPasserellidae-88%
BobolinkIcteridae-78%
Horned LarkAlaudidae-74%
Ring-necked PheasantPhasianidae-47%
Savannah SparrowPasserellidae-5%
Grasshopper SparrowPasserellidae-1%

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