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Species · Massachusetts · BBS 2025 Release · 1966–2024

Carolina Wren Population Trend in Massachusetts

All statesForest birds

Carolina Wren in Massachusetts has surged: up 67× on the route-weighted index since 1971.

67×Since 1971TrendPercent 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 →
27Routes 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 →
51YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Carolina Wren 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 →

Carolina Wren has surged in Massachusetts: up 67× on the route-weighted index since 1971.

Carolina Wren Population Forecast in Massachusetts

If the recent trend holds, Carolina Wren in Massachusetts is projected to fall about 30% by 2029 — from 10 in 2024 to a central estimate of 7.3 (95% range 4.2–10). A 5-year backtest shows a typical error of ±40.1%, with 20% of held-out values landing inside the 95% band.

-30%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 →
7.3Projected 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 →
4.2–1095% 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 →
±40.1%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, Carolina Wren in Massachusetts is projected to fall about 30% by 2029 — from 10 in 2024 to a central estimate of 7.3 (95% range 4.2–10). A 5-year backtest shows a typical error of ±40.1%, with 20% 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 →
20256.73.79.8
20266.93.89.9
20277.04.010
20287.24.110
20297.34.210

Carolina Wren Survey Routes in Massachusetts

Routes recording Carolina Wren 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 →
Marion4220241971
Gay Head2420241996
Prattville2120191966
Maynard1920221990
Mansfield1820241975
Wellfleet 21520242016
Newburyport1220221993
Holden820241992
N. Andover820242002
Monterey720242019
Littleton620241992
Belchertown620242005
S Barre620242001
Warren 2620242010
E Dennis520211970
Sheffield520222002
Brockton420191989
N Oxford420241994
Chilmark319831971
Wellfleet320071987
N Orange320242014
Chesterfield320241984
Warren220091985
Ware River120142013
Cape Cod Ns119991991

Carolina Wren Population Trend in Other States

alabamaarkansasconnecticutdelawarefloridageorgiaillinoisindianaiowakansaskentuckylouisianamainemarylandmichiganminnesotamississippimissourinebraskanew-hampshirenew-jerseynew-yorknorth-carolinaohiooklahomapennsylvaniarhode-islandsouth-carolinatennesseetexasvermontvirginiawest-virginiawisconsin

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