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

Pine Warbler Population Trend in Delaware

All statesForest birds

Pine Warbler in Delaware has surged: up 439% on the route-weighted index since 1968.

+439%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 →
16Routes 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 →
58YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Pine 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 increasecomputed 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 →

Pine Warbler has surged in Delaware: up 438% on the route-weighted index since 1968.

Pine Warbler Population Forecast in Delaware

If the recent trend holds, Pine Warbler in Delaware is projected to fall about 17% by 2029 — from 7.8 in 2024 to a central estimate of 6.5 (95% range 2.9–10). A 5-year backtest shows a typical error of ±43.1%, with 20% of held-out values landing inside the 95% band.

-17%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 →
6.5Projected 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 →
2.9–1095% 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 →
±43.1%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, Pine Warbler in Delaware is projected to fall about 17% by 2029 — from 7.8 in 2024 to a central estimate of 6.5 (95% range 2.9–10). A 5-year backtest shows a typical error of ±43.1%, with 20% 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 →
20256.12.59.7
20266.22.69.8
20276.32.79.9
20286.42.89.9
20296.52.910

Pine Warbler Survey Routes in Delaware

Routes recording Pine 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 →
Pepperbox2020161998
Millsboro1620242017
Pepperbox 21420242017
Holleyville920041966
Milton 2920172017
Frederica820141966
Holleyville 2720242006
Georgetown620221992
Frankford320121966
Harrington220241966
Lowes Xrds219911966
Bethany Bch219901966
Milton220161970
Mt Pleasant120061966
Dover119751975
Blackbird120092007

Pine Warbler Population Trend in Other States

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

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