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Species · Massachusetts · BBS 2025 Release · 1966–2024

Worm-eating Warbler Population Trend in Massachusetts

All statesForest birds

Worm-eating Warbler in Massachusetts has surged: up 93% on the route-weighted index since 1992.

+93%Since 1992TrendPercent 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 →
5Routes 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 →
13YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Worm-eating Warbler 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 →

Worm-eating Warbler has surged in Massachusetts: up 93% on the route-weighted index since 1992.

Worm-eating Warbler Survey Routes in Massachusetts

Routes recording Worm-eating Warbler 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 →
Warren 2320102010
Sheffield220221991
Warren120041992
N Orange119831983
Monterey120242024

Worm-eating Warbler Population Trend in Other States

alabamaarkansasconnecticutdelawaregeorgiaillinoisindianaiowakentuckylouisianamarylandmississippimissourinew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvirginiawest-virginiawisconsin

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