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Species · Massachusetts · BBS 2025 Release · 1966–2024

Mute Swan Population Trend in Massachusetts

All statesWaterfowl

Mute Swan in Massachusetts has surged: up 93% on the route-weighted index since 1981.

+93%Since 1981TrendPercent 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 →
11Routes 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 →
23YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Mute Swan 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 →

Mute Swan has surged in Massachusetts: up 93% on the route-weighted index since 1981.

Mute Swan Population Forecast in Massachusetts

If the recent trend holds, Mute Swan in Massachusetts is projected to rise about 16% by 2029 — from 0.27 in 2024 to a central estimate of 0.31 (95% range 0.03–0.59). A 5-year backtest shows a typical error of ±81.2%, with 100% of held-out values landing inside the 95% band.

+16%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 →
0.31Projected 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 →
0.03–0.5995% 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 →
±81.2%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, Mute Swan in Massachusetts is projected to rise about 16% by 2029 — from 0.27 in 2024 to a central estimate of 0.31 (95% range 0.03–0.59). A 5-year backtest shows a typical error of ±81.2%, with 100% of held-out values landing inside the 95% band.19712029
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 →
20250.290.010.57
20260.300.020.57
20270.300.020.58
20280.310.030.58
20290.310.030.59

Mute Swan Survey Routes in Massachusetts

Routes recording Mute Swan 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 →
Brockton319921992
Chilmark219831971
Marion220241998
Littleton220112011
Mansfield220161999
Holden220182009
N. Andover220242024
E Dennis120112001
Maynard120172017
Wellfleet 2120172017
Warren 2120182018

Mute Swan Population Trend in Other States

californiaconnecticutdelawareillinoisindianakentuckymarylandmichiganminnesotanew-hampshirenew-jerseynew-yorkohiopennsylvaniarhode-islandvirginiawisconsin

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