BirdAnalyst
Species · Delaware · BBS 2026 Release · 1966–2025

Willet Population Trend in Delaware

All statesShorebirds

Willet in Delaware has increased: up 29% on the route-weighted index since 1968.

+29%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 →
9Routes 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 Willet 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 Willet in Delaware. See the full index history below.

Willet Population Forecast in Delaware

If the recent trend holds, Willet in Delaware is projected to fall about 33% by 2030 — from 5.2 in 2025 to a central estimate of 3.5 (95% range 0.00–10). A 5-year backtest shows a typical error of ±24.6%, with 100% of held-out values landing inside the 95% band.

-33%Change by 2030TrendPercent 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 →
3.5Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–1095% 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 →
±24.6%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, Willet in Delaware is projected to fall about 33% by 2030 — from 5.2 in 2025 to a central estimate of 3.5 (95% range 0.00–10). A 5-year backtest shows a typical error of ±24.6%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20263.70.0010
20273.60.0010
20283.60.0010
20293.50.0010
20303.50.0010

Willet Survey Routes in Delaware

Routes recording Willet 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 →
Bethany Bch8419901966
Harrington2020251966
Milton1819751971
Lowes Xrds819911967
Blackbird620251995
Pepperbox 2520252017
Dover219791968
Pepperbox220161998
Georgetown220221992

Willet Population Trend in Other States

alabamacaliforniacoloradoconnecticutfloridaidaholouisianamainemarylandmassachusettsminnesotamontananebraskanevadanew-jerseynew-yorknorth-carolinanorth-dakotaoregonsouth-carolinasouth-dakotatexasutahvirginiawyoming

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.