BirdAnalyst
Species · Massachusetts · BBS 2025 Release · 1966–2024

Purple Finch Population Trend in Massachusetts

All statesGeneralists

Purple Finch in Massachusetts has collapsed: down 84% on the route-weighted index since 1968.

-84%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 →
29Routes 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 Purple Finch 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 →

Purple Finch has collapsed in Massachusetts: down 84% on the route-weighted index since 1968.

Purple Finch Population Forecast in Massachusetts

If the recent trend holds, Purple Finch in Massachusetts is projected to fall about 15% by 2029 — from 0.47 in 2024 to a central estimate of 0.40 (95% range 0.00–1.3). A 5-year backtest shows a typical error of ±163.2%, with 100% of held-out values landing inside the 95% band.

-15%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 →
0.40Projected 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 →
0.00–1.395% 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 →
±163.2%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, Purple Finch in Massachusetts is projected to fall about 15% by 2029 — from 0.47 in 2024 to a central estimate of 0.40 (95% range 0.00–1.3). A 5-year backtest shows a typical error of ±163.2%, with 100% 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 →
20250.500.001.4
20260.470.001.4
20270.450.001.4
20280.420.001.3
20290.400.001.3

Purple Finch Survey Routes in Massachusetts

Routes recording Purple Finch 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 →
Chilmark619811969
Brockton620151969
Cummington620141968
Hancock420151997
N Oxford319791968
Holden320241977
N. Andover319951995
Prattville220051966
Chesterfield220241967
Pittsfield220161968
Cummington 2220242015
E Dennis120001969
Marion120001966
Wellfleet119981966
Newburyport119921967
Maynard119881968
Littleton120211969
Mansfield120041970
Princeton119761969
E Pepperell119911966
Belchertown120181967
Warren119891968
S Barre120021968
N Orange120231968
Cheshire119881969

Purple Finch Population Trend in Other States

alaskacaliforniaconnecticutindianamainemarylandmichiganminnesotanew-hampshirenew-jerseynew-yorknorth-dakotaohiooregonpennsylvaniarhode-islandvermontwashingtonwest-virginiawisconsin

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