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Species · Tennessee · BBS 2025 Release · 1966–2024

Cliff Swallow Population Trend in Tennessee

All statesAerial insectivores

Cliff Swallow in Tennessee has surged: up 53× on the route-weighted index since 1968.

53×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 →
58YearsYears 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 53× 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 49% by 2029 — from 28 in 2024 to a central estimate of 14 (95% range 7.7–21). A 5-year backtest shows a typical error of ±32.5%, with 40% of held-out values landing inside the 95% band.

-49%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 →
14Projected 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 →
7.7–2195% 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 →
±32.5%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, Cliff Swallow in Tennessee is projected to fall about 49% by 2029 — from 28 in 2024 to a central estimate of 14 (95% range 7.7–21). A 5-year backtest shows a typical error of ±32.5%, with 40% 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 →
2025136.620
2026146.920
2027147.121
2028147.421
2029147.721

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 →
Collinwood19220241975
Pawpaw 211420232013
White House11020192008
Silerton10020242022
Jefferson Cty9820111966
Mansfield8020242013
Lewis Forest6020241999
Wrigley5820221994
Moscow5020242023
Big Sandy4720241974
Pond Creek3520241968
Trenton3020232021
Cornpone3020242005
Soddy2619811967
Jones Gap2220192006
Belotes Bend2020181995
Tullahoma1920151994
Humboldt1720242021
Peytonsville1620222021
Trace Lewis1220172013
Campbellsville1120171992
Bradyville820172003
Silver Pt820241991
Allens Brdge820232008
Indian Mound 2820182007

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 2026-05-22.