BirdAnalyst
Species · North Carolina · BBS 2025 Release · 1966–2024

Forster's Tern Population Trend in North Carolina

All statesWetland birds

Forster's Tern in North Carolina has declined: down 32% on the route-weighted index since 1973.

-32%Since 1973TrendPercent 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 →
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 Forster's Tern Trends in North CarolinaNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Forster's Tern in North Carolina. See the full index history below.

Forster's Tern Population Forecast in North Carolina

If the recent trend holds, Forster's Tern in North Carolina is projected to rise about 117% by 2028 — from 0.06 in 2023 to a central estimate of 0.13 (95% range 0.00–0.56). A 5-year backtest shows a typical error of ±160.9%, with 100% of held-out values landing inside the 95% band.

+117%Change by 2028TrendPercent 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 →
0.13Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.5695% 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 →
±160.9%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, Forster's Tern in North Carolina is projected to rise about 117% by 2028 — from 0.06 in 2023 to a central estimate of 0.13 (95% range 0.00–0.56). A 5-year backtest shows a typical error of ±160.9%, with 100% of held-out values landing inside the 95% band.19712028
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 →
20240.150.000.58
20250.140.000.58
20260.140.000.57
20270.140.000.57
20280.130.000.56

Forster's Tern Survey Routes in North Carolina

Routes recording Forster's Tern in North Carolina.
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 →
Merrimon320231971
Myrtle Grove320172013
Milltail Cr320221993
Mattamuskeet320192001
Supply220002000
Newport120231995

Forster's Tern Population Trend in Other States

alabamacaliforniacoloradodelawarefloridageorgiaidahoillinoisindianaiowakansaslouisianamarylandmichiganminnesotamontananebraskanevadanew-jerseynew-yorknorth-dakotaoregonsouth-carolinasouth-dakotatexasutahvirginiawashingtonwisconsinwyoming

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