BirdAnalyst
Species · South Dakota · BBS 2025 Release · 1966–2024

Tree Swallow Population Trend in South Dakota

All statesAerial insectivores

Tree Swallow in South Dakota has surged: up 612% on the route-weighted index since 1970.

+612%Since 1970TrendPercent 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 →
53Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Tree Swallow 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 →

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 →

Tree Swallow has surged in South Dakota: up 612% on the route-weighted index since 1970.

Tree Swallow Population Forecast in South Dakota

If the recent trend holds, Tree Swallow in South Dakota is projected to rise about 140% by 2029 — from 1.5 in 2024 to a central estimate of 3.6 (95% range 0.34–6.9). A 5-year backtest shows a typical error of ±147.8%, with 100% of held-out values landing inside the 95% band.

+140%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 →
3.6Projected 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 →
0.34–6.995% 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 →
±147.8%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, Tree Swallow in South Dakota is projected to rise about 140% by 2029 — from 1.5 in 2024 to a central estimate of 3.6 (95% range 0.34–6.9). A 5-year backtest shows a typical error of ±147.8%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20253.30.086.6
20263.40.146.7
20273.50.216.7
20283.50.276.8
20293.60.346.9

Tree Swallow Survey Routes in South Dakota

Routes recording Tree Swallow 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 →
Isabel8820151990
Promise4520151986
Rochford1520181997
Lennox1320231996
Rosebud1320112006
Badlands1320121984
Turton1320232008
Black Fox1120172003
Volga1020241968
Wilmot820241969
Ft Thompson720071977
Roswell620141969
Tripp520241999
Raymond520211984
Volunteer520171981
Cedar Pass520162012
Lacreek520231991
Howard420241990
White Lake420111993
Veblen420231969
Gettysburg420232000
Laplant420112011
Englewood420211994
Lane 2420142000
Geddes320121971

Tree Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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