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Species · Delaware · BBS 2025 Release · 1966–2024

Yellow-throated Warbler Population Trend in Delaware

All statesForest birds

Yellow-throated Warbler in Delaware has surged: up 107% on the route-weighted index since 1970.

+107%Since 1970TrendPercent 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 →
10Routes 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 →
38YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Yellow-throated 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 →

Yellow-throated Warbler has surged in Delaware: up 107% on the route-weighted index since 1970.

Yellow-throated Warbler Population Forecast in Delaware

If the recent trend holds, Yellow-throated Warbler in Delaware is projected to rise about 70% by 2029 — from 0.20 in 2024 to a central estimate of 0.34 (95% range 0.03–0.64). A 5-year backtest shows a typical error of ±31%, with 80% of held-out values landing inside the 95% band.

+70%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 →
0.34Projected 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 →
0.03–0.6495% 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 →
±31%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, Yellow-throated Warbler in Delaware is projected to rise about 70% by 2029 — from 0.20 in 2024 to a central estimate of 0.34 (95% range 0.03–0.64). A 5-year backtest shows a typical error of ±31%, with 80% of held-out values landing inside the 95% band.19672029
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 →
20250.330.020.63
20260.330.020.63
20270.330.030.64
20280.340.030.64
20290.340.030.64

Yellow-throated Warbler Survey Routes in Delaware

Routes recording Yellow-throated 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 →
Milton 2320172017
Holleyville219951980
Harrington120241975
Frederica119931993
Frankford119691969
Lowes Xrds119801967
Blackbird120232023
Pepperbox120082008
Georgetown120222018
Pepperbox 2120212017

Yellow-throated Warbler Population Trend in Other States

alabamaarkansascaliforniafloridageorgiaillinoisindianaiowakansaskentuckylouisianamarylandmichiganmississippimissourinew-jerseynorth-carolinaohiooklahomaoregonpennsylvaniasouth-carolinatennesseetexasvirginiawest-virginiawisconsin

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