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Species · Tennessee · BBS 2026 Release · 1966–2025

Cliff Swallow Population Trend in Tennessee

All statesAerial insectivores

Cliff Swallow in Tennessee has surged: up 61× on the route-weighted index since 1968.

61×Since 1968TrendPercent 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 →
38Routes 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 →
59YearsYears 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 TennesseeNotable 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 Tennessee: up 61× on the route-weighted index since 1968.

Cliff Swallow Population Forecast in Tennessee

If the recent trend holds, Cliff Swallow in Tennessee is projected to fall about 43% by 2030 — from 27 in 2025 to a central estimate of 16 (95% range 8.3–23). A 5-year backtest shows a typical error of ±35%, with 40% of held-out values landing inside the 95% band.

-43%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 →
16Projected 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 →
8.3–2395% 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 →
±35%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 Tennessee is projected to fall about 43% by 2030 — from 27 in 2025 to a central estimate of 16 (95% range 8.3–23). A 5-year backtest shows a typical error of ±35%, with 40% of held-out values landing inside the 95% band.19662030
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 →
2026147.122
2027157.422
2028157.722
2029158.023
2030168.323

Cliff Swallow Survey Routes in Tennessee

Routes recording Cliff Swallow in Tennessee.
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 →
Big Sandy13820251974
White House11020192008
Silerton10020242022
Jefferson Cty9820111966
Collinwood9520251975
Pawpaw 28420252013
Tiptonville7520251999
Wrigley5820221994
Pond Creek4220251968
Moscow3520252023
Trenton3020232021
Cornpone3020242005
Mansfield2820252013
Lewis Forest2720251999
Soddy2619811967
Jones Gap2220192006
Belotes Bend2020181995
Tullahoma1920151994
Peytonsville1620222021
Humboldt1520252021
Trace Lewis1220172013
Campbellsville1120171992
Bradyville820172003
Silver Pt820241991
Allens Brdge820232008

Cliff Swallow Population Trend in Other States

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

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