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

Chestnut-sided Warbler In Piedmont

All regionsPiedmontForest birds

Chestnut-sided Warbler in Piedmont has fallen sharply: down 75% on the route-weighted index since 1971.

-75%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 →
19Routes 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 →
39YearsYears 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 →

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 →

Chestnut-sided Warbler has fallen sharply in Piedmont: down 75% on the route-weighted index since 1971.

Forecast

If the recent trend holds, Chestnut-sided Warbler in Piedmont is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.07). A 5-year backtest shows a typical error of ±84.7%, with 100% of held-out values landing inside the 95% band.

n/aChange 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 →
0.02Projected 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 →
0.00–0.0795% 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 →
±84.7%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, Chestnut-sided Warbler in Piedmont is projected to stay roughly flat through 2029, near 0.02 (95% range 0.00–0.07). A 5-year backtest shows a typical error of ±84.7%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.020.000.07
20260.020.000.07
20270.020.000.07
20280.020.000.07
20290.020.000.07

Routes In Piedmont

Routes recording Chestnut-sided 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 →
TrymeVIRGINIA52000
Doe RunPENNSYLVANIA22005
ElamsvilleVIRGINIA21979
FowblesburgMARYLAND11969
EkloMARYLAND11967
SandbrookNEW-JERSEY12005
CrotonNEW-JERSEY12007
PottersvilleNEW-JERSEY12018
GilletteNEW-JERSEY12024
Croton 2NEW-JERSEY12023
CopelandNORTH-CAROLINA11969
CallNORTH-CAROLINA11971
SawmillNORTH-CAROLINA12018
AspersPENNSYLVANIA11978
West GrovePENNSYLVANIA11972
Mount JoyPENNSYLVANIA11997
Mt Gretna 2PENNSYLVANIA12017
Brick TavernPENNSYLVANIA12003
IrisburgVIRGINIA12004

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