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

Yellow Warbler Population Trend in Delaware

All statesForest birds

Yellow Warbler in Delaware has edged down: down 11% on the route-weighted index since 1968.

-11%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 →
14Routes 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 →
57YearsYears 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 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 →

No notable trend signals for Yellow Warbler in Delaware. See the full index history below.

Yellow Warbler Population Forecast in Delaware

If the recent trend holds, Yellow Warbler in Delaware is projected to rise about 12% by 2029 — from 1.0 in 2024 to a central estimate of 1.1 (95% range 0.00–2.3). A 5-year backtest shows a typical error of ±106.8%, with 100% of held-out values landing inside the 95% band.

+12%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 →
1.1Projected 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 →
0.00–2.395% 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 →
±106.8%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, Yellow Warbler in Delaware is projected to rise about 12% by 2029 — from 1.0 in 2024 to a central estimate of 1.1 (95% range 0.00–2.3). A 5-year backtest shows a typical error of ±106.8%, 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 →
20251.10.002.3
20261.10.002.3
20271.10.002.3
20281.10.002.3
20291.10.002.3

Yellow Warbler Survey Routes in Delaware

Routes recording Yellow 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 →
Frankford420081968
Dover219791968
Lowes Xrds219771970
Bethany Bch219891966
Blackbird220241994
Holleyville 2220242024
Mt Pleasant120121966
Wilmington120111967
Harrington120241966
Frederica120071966
Holleyville119971969
Milton120141970
Pepperbox120161999
Georgetown120171992

Yellow Warbler Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutfloridageorgiaidahoillinoisindianaiowakansaskentuckymainemarylandmassachusettsmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-carolinasouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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