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

Cerulean Warbler In Piedmont

All regionsPiedmontForest birds

Cerulean Warbler in Piedmont has collapsed: down 83% on the route-weighted index since 1968.

-83%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 →
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 →
46YearsYears 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 →

Cerulean Warbler has collapsed in Piedmont: down 83% on the route-weighted index since 1968.

Forecast

If the recent trend holds, Cerulean Warbler in Piedmont is projected to stay roughly flat through 2029, near 0.01 (95% range 0.00–0.05). A 5-year backtest shows a typical error of ±34.7%, 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 →
0.01Projected 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 →
0.00–0.0595% 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 →
±34.7%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, Cerulean Warbler in Piedmont is projected to stay roughly flat through 2029, near 0.01 (95% range 0.00–0.05). A 5-year backtest shows a typical error of ±34.7%, 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 →
20250.010.000.06
20260.010.000.06
20270.010.000.06
20280.010.000.05
20290.010.000.05

Routes In Piedmont

Routes recording Cerulean 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 →
MillervilleALABAMA21971
TheodoreMARYLAND22013
EmmitsburgMARYLAND11984
OlneyMARYLAND11998
Bachman MillMARYLAND11984
Upper XrdsMARYLAND11972
Van BibberMARYLAND12011
WheatonMARYLAND11993
IjamsvilleMARYLAND11997
EarltonMARYLAND12024
Bald FriarMARYLAND11996
LabottPENNSYLVANIA11983
TrymeVIRGINIA11984
PartlowVIRGINIA11977
CovesvilleVIRGINIA11968
Carters BrdgVIRGINIA11968
ShipmanVIRGINIA12023
ElamsvilleVIRGINIA12010
IrisburgVIRGINIA11994

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