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

Cliff Swallow Population Trend in West Virginia

All statesAerial insectivores

Cliff Swallow in West Virginia has collapsed: down 94% on the route-weighted index since 1971.

-94%Since 1971TrendPercent 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 →
26Routes 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 →
49YearsYears 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 West 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 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 West Virginia: down 94% on the route-weighted index since 1971.

Cliff Swallow Population Forecast in West Virginia

If the recent trend holds, Cliff Swallow in West Virginia is projected to rise about 89% by 2029 — from 0.05 in 2024 to a central estimate of 0.10 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±46.6%, with 100% of held-out values landing inside the 95% band.

+89%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 →
0.10Projected 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 →
0.00–1.495% 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 →
±46.6%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 West Virginia is projected to rise about 89% by 2029 — from 0.05 in 2024 to a central estimate of 0.10 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±46.6%, with 100% of held-out values landing inside the 95% band.19692029
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 →
20250.140.001.4
20260.130.001.4
20270.120.001.4
20280.110.001.4
20290.100.001.4

Cliff Swallow Survey Routes in West Virginia

Routes recording Cliff Swallow in West 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 →
Sleepy Creek3519701969
Hix620211995
Olcott420222017
Green Bank420231978
Rio419851984
Meadland320232014
Lost River320152015
Shanghai320142014
Bowden220002000
Pt Pleasant220232017
Hubbardstown220071983
Spencer220151990
Paradise220142010
Moundsville220022002
Monongah220032003
Albright219711971
Meadowville220242010
Nicut120081999
Bismark120182018
Valley Head120092009
Sugar Grove120151970
Mo Of Seneca119891989
Bebee120132008
Martinsburg120041975
Ruthbelle120191976

Cliff Swallow Population Trend in Other States

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