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

Least Tern Population Trend in Kentucky

All statesWetland birds

Least Tern in Kentucky has surged: up 126% on the route-weighted index since 1978.

+126%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 →
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 →
18YearsYears 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 KentuckyNotable 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 increasecomputed 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 surged in Kentucky: up 126% on the route-weighted index since 1978.

Least Tern Population Forecast in Kentucky

If the recent trend holds, Least Tern in Kentucky is projected to fall about 57% by 2019 — from 0.29 in 2014 to a central estimate of 0.12 (95% range 0.00–0.30). A 5-year backtest shows a typical error of ±140.8%, with 100% of held-out values landing inside the 95% band.

-57%Change 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 →
0.12Projected 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 →
0.00–0.3095% 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 →
±140.8%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 Kentucky is projected to fall about 57% by 2019 — from 0.29 in 2014 to a central estimate of 0.12 (95% range 0.00–0.30). A 5-year backtest shows a typical error of ±140.8%, with 100% of held-out values landing inside the 95% band.19672019
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 →
20150.120.000.30
20160.120.000.30
20170.120.000.30
20180.120.000.30
20190.120.000.30

Least Tern Survey Routes in Kentucky

Routes recording Least Tern in Kentucky.
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 →
Bardwell 21020142010
Joy320102001
Bardwell120001967

Least Tern Population Trend in Other States

alabamaarkansascaliforniacoloradodelawarefloridageorgiaillinoiskansaslouisianamainemarylandmassachusettsmississippimissourinebraskanew-jerseynew-yorknorth-carolinaoklahomasouth-carolinatennesseetexasvirginia

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