BirdAnalyst
Species · New Jersey · BBS 2025 Release · 1966–2024

Clapper Rail Population Trend in New Jersey

All statesWetland birds

Clapper Rail in New Jersey has surged: up 186% on the route-weighted index since 1981.

+186%Since 1981TrendPercent 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 →
3Routes 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 →
35YearsYears 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 New JerseyNotable 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 New Jersey: up 186% on the route-weighted index since 1981.

Clapper Rail Population Forecast in New Jersey

If the recent trend holds, Clapper Rail in New Jersey is projected to stay roughly flat through 2029, near 0.57 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±34%, with 100% of held-out values landing inside the 95% band.

+8%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 →
0.57Projected 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 →
0.00–1.295% 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 →
±34%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 New Jersey is projected to stay roughly flat through 2029, near 0.57 (95% range 0.00–1.2). A 5-year backtest shows a typical error of ±34%, with 100% of held-out values landing inside the 95% band.19792029
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 →
20250.560.001.2
20260.560.001.2
20270.560.001.2
20280.560.001.2
20290.570.001.2

Clapper Rail Survey Routes in New Jersey

Routes recording Clapper Rail in New Jersey.
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 →
Ocean City1120241979
Six Points220191984
Greenwich120011996

Clapper Rail Population Trend in Other States

alabamaconnecticutdelawarefloridageorgialouisianamarylandnew-yorknorth-carolinasouth-carolinatexasvirginia

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