BirdAnalyst
Species · West Virginia · BBS 2026 Release · 1966–2025

Mourning Warbler Population Trend in West Virginia

All statesForest birds

Mourning Warbler in West Virginia has surged: up 275% on the route-weighted index since 1976.

+275%Since 1976TrendPercent 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 →
12Routes 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 Mourning Warbler 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 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 →

Mourning Warbler has surged in West Virginia: up 275% on the route-weighted index since 1976.

Mourning Warbler Population Forecast in West Virginia

If the recent trend holds, Mourning Warbler in West Virginia is projected to rise about 13% by 2030 — from 0.12 in 2025 to a central estimate of 0.13 (95% range 0.00–0.38). A 5-year backtest shows a typical error of ±58.1%, with 100% of held-out values landing inside the 95% band.

+13%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 →
0.13Projected 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 →
0.00–0.3895% 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 →
±58.1%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, Mourning Warbler in West Virginia is projected to rise about 13% by 2030 — from 0.12 in 2025 to a central estimate of 0.13 (95% range 0.00–0.38). A 5-year backtest shows a typical error of ±58.1%, with 100% of held-out values landing inside the 95% band.19732030
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 →
20260.140.000.38
20270.130.000.38
20280.130.000.38
20290.130.000.38
20300.130.000.38

Mourning Warbler Survey Routes in West Virginia

Routes recording Mourning Warbler 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 →
Wymer320091995
Dailey220251973
Glady220232008
Bemis220232001
Valley Head220182016
Glade Run119971988
Bowden120232000
Glade Run 2120242009
Canaan120051980
Three Forks120251996
Richwood120251980
Green Bank120251977

Mourning Warbler Population Trend in Other States

connecticutillinoisindianamainemarylandmassachusettsmichiganminnesotanew-hampshirenew-yorknorth-dakotaohiopennsylvaniavermontwisconsin

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