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Species · Maryland · BBS 2025 Release · 1966–2024

Clapper Rail Population Trend in Maryland

All statesWetland birds

Clapper Rail in Maryland has surged: up 14× on the route-weighted index since 1969.

14×Since 1969TrendPercent 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 →
5Routes In StateSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
49YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Clapper Rail Trends in MarylandNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

long arc increasecomputed 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 →

Clapper Rail has surged in Maryland: up 14× on the route-weighted index since 1969.

Clapper Rail Population Forecast in Maryland

If the recent trend holds, Clapper Rail in Maryland is projected to fall about 27% by 2029 — from 0.48 in 2024 to a central estimate of 0.35 (95% range 0.18–0.51). A 5-year backtest shows a typical error of ±28.8%, with 80% of held-out values landing inside the 95% band.

-27%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 →
0.35Projected 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 →
0.18–0.5195% 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 →
±28.8%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, Clapper Rail in Maryland is projected to fall about 27% by 2029 — from 0.48 in 2024 to a central estimate of 0.35 (95% range 0.18–0.51). A 5-year backtest shows a typical error of ±28.8%, with 80% of held-out values landing inside the 95% band.19672029
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 →
20250.330.170.49
20260.330.170.50
20270.340.170.50
20280.340.180.51
20290.350.180.51

Clapper Rail Survey Routes in Maryland

Routes recording Clapper Rail in Maryland.
Recent countThe raw number of individuals recorded on this route in its most recent survey year. A single-route tally, not a trend.Full methodology →
Honga1020241967
Madison920241972
Berlin219861981
Melitota119951995
Cokesbury120242014

Clapper Rail Population Trend in Other States

alabamaconnecticutdelawarefloridageorgialouisiananew-jerseynew-yorknorth-carolinasouth-carolinatexasvirginia

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