BirdAnalyst
Guild · New Hampshire · BBS 2025 Release · 1966–2024

Wetland Birds In New Hampshire

All statesNew Hampshire

8 species in this guild. As a group they are -89%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 collapsed in New Hampshire, down 89% since 1968.

Forecast

If the recent trend holds, Wetland birds in New Hampshire is projected to fall about 100% by 2029 — from 0.33 in 2024 to a central estimate of 0.00 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±273.1%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–1.895% 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 →
±273.1%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 100% by 2029 — from 0.33 in 2024 to a central estimate of 0.00 (95% range 0.00–1.8). A 5-year backtest shows a typical error of ±273.1%, 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 →
20250.000.001.8
20260.000.001.8
20270.000.001.8
20280.000.001.8
20290.000.001.8

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%
Ring-billed GullLaridae-54%
American BitternArdeidae-50%
Green HeronArdeidae-37%
Double-crested CormorantPhalacrocoracidae-6%
Great Blue HeronArdeidae+83%
Common LoonGaviidae+283%

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