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Species · Tennessee · BBS 2025 Release · 1966–2024

Least Tern Population Trend in Tennessee

All statesWetland birds

Least Tern in Tennessee has declined: down 28% on the route-weighted index since 1968.

-28%Since 1968TrendPercent 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 →
34YearsYears 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 TennesseeNotable 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 Least Tern in Tennessee. See the full index history below.

Least Tern Population Forecast in Tennessee

If the recent trend holds, Least Tern in Tennessee is projected to rise about 40% by 2027 — from 0.13 in 2022 to a central estimate of 0.18 (95% range 0.00–0.58). A 5-year backtest shows a typical error of ±322.3%, with 100% of held-out values landing inside the 95% band.

+40%Change 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 →
0.18Projected 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 →
0.00–0.5895% 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 →
±322.3%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 Tennessee is projected to rise about 40% by 2027 — from 0.13 in 2022 to a central estimate of 0.18 (95% range 0.00–0.58). A 5-year backtest shows a typical error of ±322.3%, 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 →
20230.180.000.58
20240.180.000.58
20250.180.000.58
20260.180.000.58
20270.180.000.58

Least Tern Survey Routes in Tennessee

Routes recording Least Tern in Tennessee.
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 →
Tiptonville420222007
Pawpaw220111966
Pawpaw 2220182013

Least Tern Population Trend in Other States

alabamaarkansascaliforniacoloradodelawarefloridageorgiaillinoiskansaskentuckylouisianamainemarylandmassachusettsmississippimissourinebraskanew-jerseynew-yorknorth-carolinaoklahomasouth-carolinatexasvirginia

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