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

Common Tern Population Trend in North Carolina

All statesWetland birds

Common Tern in North Carolina has collapsed: down 75% on the route-weighted index since 1969.

-75%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 →
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 Common 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 →

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 →

Common Tern has collapsed in North Carolina: down 75% on the route-weighted index since 1969.

Common Tern Population Forecast in North Carolina

If the recent trend holds, Common Tern in North Carolina is projected to stay roughly flat through 2019, near 0.00 (95% range 0.00–0.46). A 5-year backtest shows a typical error of ±625.9%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2019TrendPercent 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 2019 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.4695% 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 →
±625.9%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, Common Tern in North Carolina is projected to stay roughly flat through 2019, near 0.00 (95% range 0.00–0.46). A 5-year backtest shows a typical error of ±625.9%, with 100% of held-out values landing inside the 95% band.19662019
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 →
20150.000.000.46
20160.000.000.46
20170.000.000.46
20180.000.000.46
20190.000.000.46

Common Tern Survey Routes in North Carolina

Routes recording Common 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 →
Myrtle Grove220141966
Mashoes219731972
Shallotte119811981
Merrimon120031969
Grandy119751971

Common Tern Population Trend in Other States

alabamaalaskaconnecticutdelawarefloridaidahoindianalouisianamainemarylandmassachusettsmichiganminnesotamontananew-jerseynew-yorknorth-dakotaohiorhode-islandsouth-dakotatexasvermontvirginiawashingtonwisconsinwyoming

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