BirdAnalyst
Species · Virginia · BBS 2025 Release · 1966–2024

Tree Swallow Population Trend in Virginia

All statesAerial insectivores

Tree Swallow in Virginia has surged: up 26× on the route-weighted index since 1972.

26×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 →
66Routes 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 Tree Swallow Trends in VirginiaNotable 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 Virginia: up 26× on the route-weighted index since 1972.

Tree Swallow Population Forecast in Virginia

If the recent trend holds, Tree Swallow in Virginia is projected to rise about 22% by 2029 — from 2.8 in 2024 to a central estimate of 3.3 (95% range 2.3–4.4). A 5-year backtest shows a typical error of ±18%, with 100% of held-out values landing inside the 95% band.

+22%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 →
3.3Projected 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 →
2.3–4.495% 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 →
±18%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 Virginia is projected to rise about 22% by 2029 — from 2.8 in 2024 to a central estimate of 3.3 (95% range 2.3–4.4). A 5-year backtest shows a typical error of ±18%, 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 →
20253.12.04.1
20263.12.14.2
20273.22.24.3
20283.32.24.3
20293.32.34.4

Tree Swallow Survey Routes in Virginia

Routes recording Tree Swallow in Virginia.
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 →
Brandon2520242012
Cape Charles1320181993
Blacksburg1320241988
Lake Anna1220242021
Iron Mtn.1220112011
W Augusta820241998
Natural Brid820241996
Appomattox820232000
Covington720241995
Stanley620241983
David620121988
Isom620242005
Amherst620242000
Saltville620241993
Elamsville620162003
Gladys620212001
Carters Brdg520142001
Chincoteag W520241993
Surry520061994
Iron Mountain 2520132012
Brandy Station520242017
Iron Mountain 3520142014
Star Tannery420241981
Port Royal420191993
Big Island420241996

Tree Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontwashingtonwest-virginiawisconsinwyoming

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