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

Tree Swallow Population Trend in North Dakota

All statesAerial insectivores

Tree Swallow in North Dakota has surged: up 952% on the route-weighted index since 1969.

+952%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 →
57YearsYears 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 952% 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 38% by 2029 — from 4.5 in 2024 to a central estimate of 6.2 (95% range 4.4–7.9). A 5-year backtest shows a typical error of ±41.5%, with 0% of held-out values landing inside the 95% band.

+38%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 →
6.2Projected 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 →
4.4–7.995% 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 →
±41.5%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, Tree Swallow in North Dakota is projected to rise about 38% by 2029 — from 4.5 in 2024 to a central estimate of 6.2 (95% range 4.4–7.9). A 5-year backtest shows a typical error of ±41.5%, with 0% of held-out values landing inside the 95% band.19672029
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 →
20255.84.07.5
20265.94.17.6
20276.04.27.7
20286.14.37.8
20296.24.47.9

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
Forman1320241968
Sheyenne Lk1120241982
Gorham1020181980
Stanley920241991
Denbigh920241968
Walcott820231974
Horsehead Lk820241981
Buchanan820241970
Bentley820182017
Emerado720241975
Regan720221983
Abercrombie720121974
Rolla620241969
Carpio620231968
Danzig 2620242019
Danzig520141982
Lakota 2520242010
Edgeley420241998
Kempton420171967
Wimbledon420241988
Tobacco420191991
Zap420241984
Powers Lake420241982
Turtle Mtns420241980

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 2026-05-22.