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

Willet Population Trend in Massachusetts

All statesShorebirds

Willet in Massachusetts has surged: up 227% on the route-weighted index since 1985.

+227%Since 1985TrendPercent 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 →
6Routes 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 →
33YearsYears 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 MassachusettsNotable 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 →

Willet has surged in Massachusetts: up 227% on the route-weighted index since 1985.

Willet Population Forecast in Massachusetts

If the recent trend holds, Willet in Massachusetts is projected to rise about 187% by 2029 — from 0.20 in 2024 to a central estimate of 0.57 (95% range 0.01–1.1). A 5-year backtest shows a typical error of ±134.8%, with 100% of held-out values landing inside the 95% band.

+187%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 →
0.57Projected 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 →
0.01–1.195% 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 →
±134.8%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, Willet in Massachusetts is projected to rise about 187% by 2029 — from 0.20 in 2024 to a central estimate of 0.57 (95% range 0.01–1.1). A 5-year backtest shows a typical error of ±134.8%, with 100% of held-out values landing inside the 95% band.19832029
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 →
20250.540.001.1
20260.550.001.1
20270.560.001.1
20280.570.001.1
20290.570.011.1

Willet Survey Routes in Massachusetts

Routes recording Willet in Massachusetts.
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 →
Wellfleet 2320242016
Wellfleet220052005
Gay Head220042004
Brockton220182018
Newburyport220221983
E Dennis120132012

Willet Population Trend in Other States

alabamacaliforniacoloradoconnecticutdelawarefloridaidaholouisianamainemarylandminnesotamontananebraskanevadanew-jerseynew-yorknorth-carolinanorth-dakotaoregonsouth-carolinasouth-dakotatexasutahvirginiawyoming

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