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Species · North Carolina · BBS 2025 Release · 1966–2024

Cerulean Warbler Population Trend in North Carolina

All statesForest birds

Cerulean Warbler in North Carolina has fallen sharply: down 65% on the route-weighted index since 1992.

-65%Since 1992TrendPercent 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 →
6Routes 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 →
21YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Cerulean Warbler Trends in North CarolinaNotable 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 fallen sharply in North Carolina: down 65% on the route-weighted index since 1992.

Cerulean Warbler Population Forecast in North Carolina

If the recent trend holds, Cerulean Warbler in North Carolina is projected to stay roughly flat through 2029, near 0.04 (95% range 0.00–0.12). A 5-year backtest shows a typical error of ±103.2%, 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 →
0.04Projected 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 →
0.00–0.1295% 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 →
±103.2%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 North Carolina is projected to stay roughly flat through 2029, near 0.04 (95% range 0.00–0.12). A 5-year backtest shows a typical error of ±103.2%, 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 →
20250.040.000.12
20260.040.000.12
20270.040.000.12
20280.040.000.12
20290.040.000.12

Cerulean Warbler Survey Routes in North Carolina

Routes recording Cerulean Warbler in North Carolina.
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 →
French Broad River320032002
Oteen220231992
Dortches119921992
Waterville120242014
Fontana120241969
Marshall119901990

Cerulean Warbler Population Trend in Other States

alabamaarkansasconnecticutgeorgiaillinoisindianakentuckylouisianamarylandmassachusettsmichiganminnesotamississippimissourinew-hampshirenew-jerseynew-yorkohiooklahomapennsylvaniatennesseevermontvirginiawest-virginiawisconsin

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