BirdAnalyst
Species · South Dakota · BBS 2026 Release · 1966–2025

Franklin's Gull Population Trend in South Dakota

All statesWetland birds

Franklin's Gull in South Dakota has declined: down 38% on the route-weighted index since 1969.

-38%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 →
26Routes 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 →
51YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Franklin's Gull Trends in South DakotaNotable 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 Franklin's Gull in South Dakota. See the full index history below.

Franklin's Gull Population Forecast in South Dakota

If the recent trend holds, Franklin's Gull in South Dakota is projected to rise about 166% by 2030 — from 1.1 in 2025 to a central estimate of 2.9 (95% range 0.00–11). A 5-year backtest shows a typical error of ±64.5%, with 60% of held-out values landing inside the 95% band.

+166%Change by 2030TrendPercent 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 →
2.9Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1195% 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 →
±64.5%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, Franklin's Gull in South Dakota is projected to rise about 166% by 2030 — from 1.1 in 2025 to a central estimate of 2.9 (95% range 0.00–11). A 5-year backtest shows a typical error of ±64.5%, with 60% of held-out values landing inside the 95% band.19672030
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 →
20263.00.0011
20273.00.0011
20283.00.0011
20293.00.0011
20302.90.0011

Franklin's Gull Survey Routes in South Dakota

Routes recording Franklin's Gull in South Dakota.
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 →
Tripp48820171967
Roswell10020071967
Gettysburg10020231969
Fort Pierre10019981998
Howard6020241970
White Lake5019691967
Chamberlain4420112011
Long Lake3520091970
Forbes3120251967
Lennox2620091967
Turton2620071985
Britton1420211967
Gorman1419981998
Geddes1319881967
Broadland919691969
Raymond720211968
Wilmot420241967
Volga320231967
Ft Thompson319901990
Crow Creek220221967
Laplant219901990
Cedar Pass220021973
Lane119771977
Veblen119841967
Conde119841967

Franklin's Gull Population Trend in Other States

californiacoloradoidahokansasminnesotamontananebraskanorth-dakotaoregonutahwyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.