BirdAnalyst
Guild · New Hampshire · BBS 2026 Release · 1966–2025

Wetland Birds In New Hampshire

All statesNew Hampshire

12 species in this guild. As a group they are -51%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 →

Wetland birds as a group have fallen sharply in New Hampshire, down 51% since 1968.

Wetland Birds In New Hampshire Population Forecast

If the recent trend holds, Wetland birds in New Hampshire is projected to fall about 52% by 2030 — from 2.8 in 2025 to a central estimate of 1.3 (95% range 0.00–3.1). A 5-year backtest shows a typical error of ±38.8%, with 100% of held-out values landing inside the 95% band.

-52%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 →
1.3Projected 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 →
0.00–3.195% 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 →
±38.8%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, Wetland birds in New Hampshire is projected to fall about 52% by 2030 — from 2.8 in 2025 to a central estimate of 1.3 (95% range 0.00–3.1). A 5-year backtest shows a typical error of ±38.8%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20261.50.003.3
20271.50.003.2
20281.40.003.2
20291.40.003.1
20301.30.003.1

Member Species In New Hampshire

Wetland birds species in New Hampshire.
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 →
Herring GullLaridae-100%
Great Black-backed GullLaridae-81%
American BitternArdeidae-75%
Rusty BlackbirdIcteridae-69%
Ring-billed GullLaridae-54%
Red-winged BlackbirdIcteridae-52%
Green HeronArdeidae-37%
Swamp SparrowPasserellidae-23%
Belted KingfisherAlcedinidae-22%
Double-crested CormorantPhalacrocoracidae-6%
Great Blue HeronArdeidae+80%
Common LoonGaviidae+277%

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