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Species · Delaware · BBS 2025 Release · 1966–2024

Kentucky Warbler Population Trend in Delaware

All statesForest birds

Kentucky Warbler in Delaware has collapsed: down 80% on the route-weighted index since 1968.

-80%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 →
15Routes 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 →
51YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Kentucky Warbler Trends in DelawareNotable 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 →

Kentucky Warbler has collapsed in Delaware: down 80% on the route-weighted index since 1968.

Kentucky Warbler Population Forecast in Delaware

If the recent trend holds, Kentucky Warbler in Delaware is projected to fall about 100% by 2027 — from 0.20 in 2022 to a central estimate of 0.00 (95% range 0.00–0.77). A 5-year backtest shows a typical error of ±174.8%, with 100% of held-out values landing inside the 95% band.

-100%Change by 2027TrendPercent 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 →
0.00Projected 2027 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.7795% 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 →
±174.8%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, Kentucky Warbler in Delaware is projected to fall about 100% by 2027 — from 0.20 in 2022 to a central estimate of 0.00 (95% range 0.00–0.77). A 5-year backtest shows a typical error of ±174.8%, with 100% of held-out values landing inside the 95% band.19662027
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 →
20230.000.000.77
20240.000.000.77
20250.000.000.77
20260.000.000.77
20270.000.000.77

Kentucky Warbler Survey Routes in Delaware

Routes recording Kentucky Warbler in Delaware.
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 →
Mt Pleasant120071966
Wilmington120001967
Harrington120211966
Frederica120051966
Dover119791979
Frankford120081966
Holleyville120031966
Lowes Xrds119801966
Bethany Bch119731966
Milton120161966
Blackbird120222019
Holleyville 2120072006
Pepperbox120051998
Georgetown120141992
Pepperbox 2120192017

Kentucky Warbler Population Trend in Other States

alabamaarkansasfloridageorgiaillinoisindianaiowakansaskentuckylouisianamarylandmississippimissourinew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniasouth-carolinatennesseetexasvirginiawest-virginiawisconsin

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