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

Wetland Birds In Maryland

All statesMaryland

26 species in this guild. As a group they are -42%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 declined in Maryland, down 42% since 1968.

Wetland Birds In Maryland Population Forecast

If the recent trend holds, Wetland birds in Maryland is projected to fall about 34% by 2030 — from 3.5 in 2025 to a central estimate of 2.3 (95% range 0.96–3.6). A 5-year backtest shows a typical error of ±23.3%, with 100% of held-out values landing inside the 95% band.

-34%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 →
2.3Projected 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 →
0.96–3.695% 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 →
±23.3%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 Maryland is projected to fall about 34% by 2030 — from 3.5 in 2025 to a central estimate of 2.3 (95% range 0.96–3.6). A 5-year backtest shows a typical error of ±23.3%, 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 →
20262.41.13.8
20272.41.13.7
20282.41.03.7
20292.30.993.7
20302.30.963.6

Member Species In Maryland

Wetland birds species in Maryland.
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 →
Western Cattle-EgretArdeidae-83%
Black-crowned Night HeronArdeidae-74%
Boat-tailed GrackleIcteridae-65%
Forster's TernLaridae-62%
Common TernLaridae-54%
Laughing GullLaridae-53%
Belted KingfisherAlcedinidae-51%
Green HeronArdeidae-43%
Red-winged BlackbirdIcteridae-42%
Common GallinuleRallidae-27%
Little Blue HeronArdeidae-19%
Great Black-backed GullLaridae+6%
Swamp SparrowPasserellidae+27%
Virginia RailRallidae+52%
Seaside SparrowPasserellidae+80%
King RailRallidae+86%
Great EgretArdeidae+87%
Great Blue HeronArdeidae+101%
Least TernLaridae+136%
Snowy EgretArdeidae+144%
Least BitternArdeidae+169%
Herring GullLaridae+391%
Double-crested CormorantPhalacrocoracidae+535%
Glossy IbisThreskiornithidae+702%
Ring-billed GullLaridae11×
Clapper RailRallidae14×

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