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Species · Massachusetts · BBS 2025 Release · 1966–2024

Warbling Vireo Population Trend in Massachusetts

All statesForest birds

Warbling Vireo in Massachusetts has surged: up 589% on the route-weighted index since 1968.

+589%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 →
28Routes 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 Warbling Vireo 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 →

Warbling Vireo has surged in Massachusetts: up 589% on the route-weighted index since 1968.

Warbling Vireo Population Forecast in Massachusetts

If the recent trend holds, Warbling Vireo in Massachusetts is projected to rise about 10% by 2029 — from 2.9 in 2024 to a central estimate of 3.2 (95% range 2.3–4.1). A 5-year backtest shows a typical error of ±7.3%, with 100% of held-out values landing inside the 95% band.

+10%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 →
3.2Projected 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 →
2.3–4.195% 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 →
±7.3%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, Warbling Vireo in Massachusetts is projected to rise about 10% by 2029 — from 2.9 in 2024 to a central estimate of 3.2 (95% range 2.3–4.1). A 5-year backtest shows a typical error of ±7.3%, 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 →
20253.12.23.9
20263.12.24.0
20273.12.34.0
20283.22.34.1
20293.22.34.1

Warbling Vireo Survey Routes in Massachusetts

Routes recording Warbling Vireo 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 →
Warren 2920242010
N. Andover820241995
Belchertown720241967
Maynard620221972
E Pepperell619941966
Warren520091968
Monterey520242019
Chesterfield420241973
Prattville320191995
Newburyport320221967
Sheffield320221971
Cummington 2320242015
Hancock320151997
N Oxford220241968
Princeton219761974
Pittsfield220091970
Marion120241992
Ware River120132012
Brockton120181994
Littleton120241967
Mansfield120241971
S Barre120241971
N Orange120241971
Cummington120101969
Cheshire119941970

Warbling Vireo Population Trend in Other States

alabamaalaskaarizonaarkansascaliforniacoloradoconnecticutdelawareidahoillinoisindianaiowakansaskentuckylouisianamainemarylandmichiganminnesotamississippimissourimontananebraskanevadanew-hampshirenew-jerseynew-mexiconew-yorknorth-carolinanorth-dakotaohiooklahomaoregonpennsylvaniarhode-islandsouth-dakotatennesseetexasutahvermontvirginiawashingtonwest-virginiawisconsinwyoming

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