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Species · BCR 26 · BBS 2025 Release · 1966–2024

Least Tern In Mississippi Alluvial Valley

All regionsMississippi Alluvial ValleyWetland birds

Least Tern in Mississippi Alluvial Valley has fallen sharply: down 67% on the route-weighted index since 1968.

-67%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 →
20Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
46YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 →

Least Tern has fallen sharply in Mississippi Alluvial Valley: down 67% on the route-weighted index since 1968.

Least Tern In Mississippi Alluvial Valley Population Forecast

If the recent trend holds, Least Tern in Mississippi Alluvial Valley is projected to fall about 21% by 2029 — from 0.30 in 2024 to a central estimate of 0.24 (95% range 0.00–0.75). A 5-year backtest shows a typical error of ±92.3%, with 100% of held-out values landing inside the 95% band.

-21%Change by 2029TrendPercent 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 →
0.24Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.7595% 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 →
±92.3%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 Mississippi Alluvial Valley is projected to fall about 21% by 2029 — from 0.30 in 2024 to a central estimate of 0.24 (95% range 0.00–0.75). A 5-year backtest shows a typical error of ±92.3%, with 100% of held-out values landing inside the 95% band.19662029
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 →
20250.250.000.76
20260.250.000.76
20270.240.000.76
20280.240.000.75
20290.240.000.75

Routes In Mississippi Alluvial Valley

Routes recording Least Tern in Mississippi Alluvial Valley.
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 2KENTUCKY102014
WilsonARKANSAS92024
TiptonvilleTENNESSEE42022
ShawLOUISIANA32015
DundeeMISSISSIPPI32022
GillettARKANSAS22014
BelairLOUISIANA22002
Baton RougeLOUISIANA22015
Eagle LakeMISSISSIPPI22015
HaytiMISSOURI22021
PawpawTENNESSEE22011
Pawpaw 2TENNESSEE22018
EudoraARKANSAS12009
HughesARKANSAS12021
South BendARKANSAS12012
Crowley'S RidgeARKANSAS12022
BardwellKENTUCKY12000
CarlisleLOUISIANA11988
DeventerMISSOURI12024
Cp GirardeauMISSOURI12015

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