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

Tree Swallow Population Trend in North Dakota

All statesAerial insectivores

Tree Swallow in North Dakota has surged: up 750% on the route-weighted index since 1969.

+750%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 →
48Routes 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 →
58YearsYears 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 North 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 North Dakota: up 750% on the route-weighted index since 1969.

Tree Swallow Population Forecast in North Dakota

If the recent trend holds, Tree Swallow in North Dakota is projected to rise about 184% by 2030 — from 2.1 in 2025 to a central estimate of 6.0 (95% range 4.0–8.0). A 5-year backtest shows a typical error of ±70.6%, with 60% of held-out values landing inside the 95% band.

+184%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 →
6.0Projected 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 →
4.0–8.095% 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 →
±70.6%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 North Dakota is projected to rise about 184% by 2030 — from 2.1 in 2025 to a central estimate of 6.0 (95% range 4.0–8.0). A 5-year backtest shows a typical error of ±70.6%, 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 →
20265.63.67.6
20275.73.77.7
20285.83.87.8
20295.93.97.9
20306.04.08.0

Tree Swallow Survey Routes in North Dakota

Routes recording Tree Swallow in North 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 →
Parshall10520111993
Gorham1020181980
Walcott820231974
Edgeley820251998
Bentley820182017
Abercrombie720121974
Rolla620241969
Carpio620231968
Danzig520141982
Buchanan520251970
Sheyenne Lk520251982
Turtle Mtns520251980
Kempton420171967
Emerado420251975
Cooperstown420251969
Wimbledon420241988
Tobacco420191991
Zap420241984
Glen Ullin420231996
Danzig 2420252019
Regan320231983
Ft Yates320041986
Loraine320191986
Stanley320251991
Denbigh320251968

Tree Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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