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

Tree Swallow Population Trend in North Carolina

All statesAerial insectivores

Tree Swallow in North Carolina has surged: up 22× on the route-weighted index since 1972.

22×Since 1972TrendPercent 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 →
56Routes 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 →
34YearsYears 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 CarolinaNotable 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 Carolina: up 22× on the route-weighted index since 1972.

Tree Swallow Population Forecast in North Carolina

If the recent trend holds, Tree Swallow in North Carolina is projected to fall about 33% by 2029 — from 1.5 in 2024 to a central estimate of 0.97 (95% range 0.38–1.6). A 5-year backtest shows a typical error of ±46.5%, with 20% of held-out values landing inside the 95% band.

-33%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 →
0.97Projected 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 →
0.38–1.695% 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 →
±46.5%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 Carolina is projected to fall about 33% by 2029 — from 1.5 in 2024 to a central estimate of 0.97 (95% range 0.38–1.6). A 5-year backtest shows a typical error of ±46.5%, with 20% of held-out values landing inside the 95% band.19692029
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 →
20250.890.301.5
20260.910.321.5
20270.930.341.5
20280.950.361.5
20290.970.381.6

Tree Swallow Survey Routes in North Carolina

Routes recording Tree Swallow in North Carolina.
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 →
Sturgills1720242009
Brevard1320242005
Todd1020231996
Cherokee920242011
Cullowhee820242013
Hendersonvil820242003
Oteen720242003
Siloam620242009
Lloyd Xroads620012001
Linville520241994
Bethel520182018
Fontana420242017
Sheffield420232015
Bullock420232015
Youngsville320241972
French Broad River320242003
Mcginnis Crossroad320222022
Marshall320242009
Busick220021995
Saxapahaw220182017
Oakboro220242024
Arcola220242001
Call220242014
Old Trap220112011
Cypress Lakes220172004

Tree Swallow Population Trend in Other States

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

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