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

Cliff Swallow Population Trend in Vermont

All statesAerial insectivores

Cliff Swallow in Vermont has collapsed: down 82% on the route-weighted index since 1968.

-82%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 →
25Routes 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 →
57YearsYears 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 VermontNotable 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 declinecomputed 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 collapsed in Vermont: down 82% on the route-weighted index since 1968.

Cliff Swallow Population Forecast in Vermont

If the recent trend holds, Cliff Swallow in Vermont is projected to fall about 100% by 2029 — from 0.22 in 2024 to a central estimate of 0.00 (95% range 0.00–2.2). A 5-year backtest shows a typical error of ±76.8%, with 100% of held-out values landing inside the 95% band.

-100%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 →
0.00Projected 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 →
0.00–2.295% 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 →
±76.8%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 Vermont is projected to fall about 100% by 2029 — from 0.22 in 2024 to a central estimate of 0.00 (95% range 0.00–2.2). A 5-year backtest shows a typical error of ±76.8%, with 100% 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 →
20250.000.002.2
20260.000.002.2
20270.000.002.2
20280.000.002.2
20290.000.002.2

Cliff Swallow Survey Routes in Vermont

Routes recording Cliff Swallow in Vermont.
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 →
Northfld Fls1919801980
Stowe819921992
Hardwick619941973
Grand Isle619851969
Gaysville520171979
S Wallingfrd420211980
St Johnsbury420221971
Newbury419981986
East Calais320121966
Greensboro319991967
Landgrove220171966
Shaftsbury220051968
Middlesex220241970
Waterville219801968
Colchester219981991
Marlboro119721968
North Pownal119661966
Stratton120191969
S Reading120081969
Post Mills120241967
W Rutland120091970
East Haven120241968
Fletcher120131968
Hinesburg119941969
Bristol120002000

Cliff Swallow Population Trend in Other States

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

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