BirdAnalyst
Species · Virginia · BBS 2025 Release · 1966–2024

Royal Tern Population Trend in Virginia

All statesWetland birds

Royal Tern in Virginia has collapsed: down 76% on the route-weighted index since 1978.

-76%Since 1978TrendPercent 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 →
8Routes 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 →
24YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Royal Tern Trends in VirginiaNotable 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 →

Royal Tern has collapsed in Virginia: down 76% on the route-weighted index since 1978.

Royal Tern Population Forecast in Virginia

If the recent trend holds, Royal Tern in Virginia is projected to stay roughly flat through 2027, near 0.19 (95% range 0.00–0.97). A 5-year backtest shows a typical error of ±630.1%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2027TrendPercent 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 →
0.19Projected 2027 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.9795% 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 →
±630.1%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, Royal Tern in Virginia is projected to stay roughly flat through 2027, near 0.19 (95% range 0.00–0.97). A 5-year backtest shows a typical error of ±630.1%, with 100% of held-out values landing inside the 95% band.19662027
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 →
20230.200.000.98
20240.200.000.98
20250.190.000.97
20260.190.000.97
20270.190.000.97

Royal Tern Survey Routes in Virginia

Routes recording Royal Tern in Virginia.
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 →
Cape Charles1120071993
White Stone320171981
Surry320212019
Chincoteag W220222022
Sharps219991999
Quinby120061966
Gloucester120011997
Colonial Pky119981996

Royal Tern Population Trend in Other States

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