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

Least Tern Population Trend in New Jersey

All statesWetland birds

Least Tern in New Jersey has collapsed: down 89% on the route-weighted index since 1980.

-89%Since 1980TrendPercent 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 →
6Routes 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 →
26YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Least Tern 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 declinecomputed 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 →

Least Tern has collapsed in New Jersey: down 89% on the route-weighted index since 1980.

Least Tern Population Forecast in New Jersey

If the recent trend holds, Least Tern in New Jersey is projected to fall about 100% by 2018 — from 0.06 in 2013 to a central estimate of 0.00 (95% range 0.00–0.65). A 5-year backtest shows a typical error of ±77.4%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2018TrendPercent 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 2018 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.6595% 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 →
±77.4%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, Least Tern in New Jersey is projected to fall about 100% by 2018 — from 0.06 in 2013 to a central estimate of 0.00 (95% range 0.00–0.65). A 5-year backtest shows a typical error of ±77.4%, with 100% of held-out values landing inside the 95% band.19752018
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 →
20140.000.000.65
20150.000.000.65
20160.000.000.65
20170.000.000.65
20180.000.000.65

Least Tern Survey Routes in New Jersey

Routes recording Least Tern 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 →
Toms River219751975
Cape May Ch219921992
Villas219811981
Six Points120081979
Del Haven119911991
Ocean City120131979

Least Tern Population Trend in Other States

alabamaarkansascaliforniacoloradodelawarefloridageorgiaillinoiskansaskentuckylouisianamainemarylandmassachusettsmississippimissourinebraskanew-yorknorth-carolinaoklahomasouth-carolinatennesseetexasvirginia

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