BirdAnalyst
Species · Massachusetts · BBS 2026 Release · 1966–2025

Mute Swan Population Trend in Massachusetts

All statesWaterfowl

Mute Swan in Massachusetts has surged: up 96% on the route-weighted index since 1981.

+96%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 →
24YearsYears 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 96% 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 134% by 2030 — from 0.13 in 2025 to a central estimate of 0.29 (95% range 0.01–0.57). A 5-year backtest shows a typical error of ±119.6%, with 100% of held-out values landing inside the 95% band.

+134%Change by 2030TrendPercent 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 →
0.29Projected 2030 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.01–0.5795% 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 →
±119.6%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 134% by 2030 — from 0.13 in 2025 to a central estimate of 0.29 (95% range 0.01–0.57). A 5-year backtest shows a typical error of ±119.6%, with 100% of held-out values landing inside the 95% band.19712030
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 →
20260.280.000.56
20270.280.000.56
20280.280.010.56
20290.290.010.57
20300.290.010.57

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
Wellfleet 2220252017
Mansfield220161999
Holden220182009
N. Andover220242024
E Dennis120112001
Maynard120172017
Warren 2120182018

Mute Swan Population Trend in Other States

californiaconnecticutdelawareillinoisindianakentuckymarylandmichiganminnesotanew-hampshirenew-jerseynew-yorkohiopennsylvaniarhode-islandvirginiawisconsin

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.