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Species · Massachusetts · BBS 2025 Release · 1966–2024

Canada Warbler Population Trend in Massachusetts

All statesForest birds

Canada Warbler in Massachusetts has fallen sharply: down 72% on the route-weighted index since 1969.

-72%Since 1969TrendPercent 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 →
16Routes 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 →
56YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Canada 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 declinecomputed 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 →

Canada Warbler has fallen sharply in Massachusetts: down 72% on the route-weighted index since 1969.

Canada Warbler Population Forecast in Massachusetts

If the recent trend holds, Canada Warbler in Massachusetts is projected to fall about 99% by 2029 — from 0.27 in 2024 to a central estimate of 0.00 (95% range 0.00–0.39). A 5-year backtest shows a typical error of ±92.8%, with 100% of held-out values landing inside the 95% band.

-99%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 →
0.00Projected 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 →
0.00–0.3995% 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 →
±92.8%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, Canada Warbler in Massachusetts is projected to fall about 99% by 2029 — from 0.27 in 2024 to a central estimate of 0.00 (95% range 0.00–0.39). A 5-year backtest shows a typical error of ±92.8%, with 100% of held-out values landing inside the 95% band.19672029
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 →
20250.050.000.43
20260.040.000.42
20270.020.000.41
20280.010.000.40
20290.000.000.39

Canada Warbler Survey Routes in Massachusetts

Routes recording Canada 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 →
Princeton219761969
Monterey220242019
Marion119921967
Ware River120221996
Newburyport119681967
Belchertown120241967
Warren119981971
S Barre120051968
N Orange120191968
Cummington120141968
Chesterfield120241967
Holden119831980
Pittsfield120161968
Sheffield119991969
Cummington 2120192015
Hancock120111997

Canada Warbler Population Trend in Other States

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

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