BirdAnalyst
Species · Delaware · BBS 2025 Release · 1966–2024

Prairie Warbler Population Trend in Delaware

All statesForest birds

Prairie Warbler in Delaware has fallen sharply: down 63% on the route-weighted index since 1968.

-63%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 →
55YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Prairie 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 →

Prairie Warbler has fallen sharply in Delaware: down 62% on the route-weighted index since 1968.

Prairie Warbler Population Forecast in Delaware

If the recent trend holds, Prairie Warbler in Delaware is projected to rise about 173% by 2029 — from 0.20 in 2024 to a central estimate of 0.55 (95% range 0.00–1.6). A 5-year backtest shows a typical error of ±110.3%, with 100% of held-out values landing inside the 95% band.

+173%Change 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 →
0.55Projected 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 →
0.00–1.695% 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 →
±110.3%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, Prairie Warbler in Delaware is projected to rise about 173% by 2029 — from 0.20 in 2024 to a central estimate of 0.55 (95% range 0.00–1.6). A 5-year backtest shows a typical error of ±110.3%, 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 →
20250.590.001.6
20260.580.001.6
20270.570.001.6
20280.560.001.6
20290.550.001.6

Prairie Warbler Survey Routes in Delaware

Routes recording Prairie 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 →
Holleyville520041966
Lowes Xrds519871966
Pepperbox420161998
Bethany Bch219891978
Mt Pleasant119921966
Wilmington120111968
Harrington120241967
Frederica120081967
Dover119751975
Frankford120081966
Milton120081984
Millsboro120212017
Holleyville 2120192006
Georgetown120221992
Pepperbox 2120212019

Prairie Warbler Population Trend in Other States

alabamaarkansascaliforniaconnecticutfloridageorgiaillinoisindianakentuckylouisianamainemarylandmassachusettsmichiganmississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvermontvirginiawest-virginiawisconsin

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