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Species · Virginia · BBS 2025 Release · 1966–2024

Cliff Swallow Population Trend in Virginia

All statesAerial insectivores

Cliff Swallow in Virginia has surged: up 127% on the route-weighted index since 1969.

+127%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 →
23Routes 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 Cliff 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 →

Cliff Swallow has surged in Virginia: up 127% on the route-weighted index since 1969.

Cliff Swallow Population Forecast in Virginia

If the recent trend holds, Cliff Swallow in Virginia is projected to rise about 220% by 2029 — from 0.79 in 2024 to a central estimate of 2.5 (95% range 0.52–4.5). A 5-year backtest shows a typical error of ±160.4%, with 0% of held-out values landing inside the 95% band.

+220%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 →
2.5Projected 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 →
0.52–4.595% 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 →
±160.4%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, Cliff Swallow in Virginia is projected to rise about 220% by 2029 — from 0.79 in 2024 to a central estimate of 2.5 (95% range 0.52–4.5). A 5-year backtest shows a typical error of ±160.4%, with 0% of held-out values landing inside the 95% band.19662029
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 →
20252.40.344.4
20262.40.394.4
20272.40.434.4
20282.50.474.5
20292.50.524.5

Cliff Swallow Survey Routes in Virginia

Routes recording Cliff 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 →
Wylliesburg22020191998
Port Royal5220192008
Churchville1520241966
Brodnax1020241975
Finchley820212007
Star Tannery619831977
Gladys620241994
W Augusta419851969
Stanley420241978
Rural Retrt420142014
Concord420242023
Hall419821982
Taylorstown219851969
Jerome220182018
Covington219661966
Covesville220191977
Carters Brdg219871969
Shipman219701970
Moran220242024
Tryme119901976
Edinburg120232014
Natural Brid119871987
Branchville120142014

Cliff Swallow Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawarefloridageorgiaidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniasouth-carolinasouth-dakotatennesseetexasutahvermontwashingtonwest-virginiawisconsinwyoming

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