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Species · Massachusetts · BBS 2025 Release · 1966–2024

Blackburnian Warbler Population Trend in Massachusetts

All statesForest birds

Blackburnian Warbler in Massachusetts has surged: up 208% on the route-weighted index since 1968.

+208%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 →
19Routes 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 Blackburnian 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 →

Blackburnian Warbler has surged in Massachusetts: up 208% on the route-weighted index since 1968.

Blackburnian Warbler Population Forecast in Massachusetts

If the recent trend holds, Blackburnian Warbler in Massachusetts is projected to rise about 57% by 2029 — from 1.2 in 2024 to a central estimate of 1.9 (95% range 1.0–2.7). A 5-year backtest shows a typical error of ±74.4%, with 40% of held-out values landing inside the 95% band.

+57%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 →
1.9Projected 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 →
1.0–2.795% 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 →
±74.4%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, Blackburnian Warbler in Massachusetts is projected to rise about 57% by 2029 — from 1.2 in 2024 to a central estimate of 1.9 (95% range 1.0–2.7). A 5-year backtest shows a typical error of ±74.4%, with 40% 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 →
20251.80.942.6
20261.80.962.7
20271.80.992.7
20281.91.02.7
20291.91.02.7

Blackburnian Warbler Survey Routes in Massachusetts

Routes recording Blackburnian 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 →
Pittsfield1420161969
Cummington920141968
Chesterfield720241967
Sheffield520221971
Cummington 2420242015
N Orange320241968
Hancock320151997
Princeton219761970
Belchertown220241973
Warren219841975
Monterey220242019
Holden219891977
Marion119931993
Ware River120221994
Littleton119721972
E Pepperell119881966
S Barre120211978
Cheshire119921971
Warren 2120112011

Blackburnian Warbler Population Trend in Other States

connecticutgeorgiaindianamainemarylandmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-carolinaohiopennsylvaniarhode-islandtennesseevermontvirginiawest-virginiawisconsin

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