BirdAnalyst
Species · BCR 29 · BBS 2025 Release · 1966–2024

Black-throated Green Warbler In Piedmont

All regionsPiedmontForest birds

Black-throated Green Warbler in Piedmont has declined: down 49% on the route-weighted index since 1986.

-49%Since 1986TrendPercent 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 →
9Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
19YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

No notable trend signals for Black-throated Green Warbler in Piedmont. See the full index history below.

Black-throated Green Warbler In Piedmont Population Forecast

If the recent trend holds, Black-throated Green Warbler in Piedmont is projected to stay roughly flat through 2021, near 0.01 (95% range 0.00–0.03). A 5-year backtest shows a typical error of ±41.8%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2021TrendPercent 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 →
0.01Projected 2021 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.0395% 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 →
±41.8%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, Black-throated Green Warbler in Piedmont is projected to stay roughly flat through 2021, near 0.01 (95% range 0.00–0.03). A 5-year backtest shows a typical error of ±41.8%, with 100% of held-out values landing inside the 95% band.19722021
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 →
20170.010.000.04
20180.010.000.04
20190.010.000.03
20200.010.000.03
20210.010.000.03

Routes In Piedmont

Routes recording Black-throated Green Warbler in Piedmont.
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 →
WedoweeALABAMA22007
ElamsvilleVIRGINIA22016
Liberty CityALABAMA11982
Nixburg 2ALABAMA12011
BaldwinGEORGIA11998
Mt Gretna 2PENNSYLVANIA12014
AmherstVIRGINIA12007
ShipmanVIRGINIA11989
Pw Forest PkVIRGINIA12004

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