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Species · Massachusetts · BBS 2025 Release · 1966–2024

Mourning Warbler Population Trend in Massachusetts

All statesForest birds

Mourning Warbler in Massachusetts has edged down: down 18% on the route-weighted index since 1987.

-18%Since 1987TrendPercent 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 →
4Routes 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 Mourning 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 →

No notable trend signals for Mourning Warbler in Massachusetts. See the full index history below.

Mourning Warbler Survey Routes in Massachusetts

Routes recording Mourning 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 →
Hancock120122010
Cummington119981975
Chesterfield120151987
Pittsfield120011975

Mourning Warbler Population Trend in Other States

connecticutillinoisindianamainemarylandmichiganminnesotanew-hampshirenew-yorknorth-dakotaohiopennsylvaniavermontwest-virginiawisconsin

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