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

Warbling Vireo Population Trend in Massachusetts

All statesForest birds

Warbling Vireo in Massachusetts has surged: up 573% on the route-weighted index since 1968.

+573%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 →
59YearsYears 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 573% 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 stay roughly flat through 2030, near 3.3 (95% range 2.4–4.2). A 5-year backtest shows a typical error of ±8.1%, with 100% of held-out values landing inside the 95% band.

+5%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 →
3.3Projected 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 →
2.4–4.295% 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 →
±8.1%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, Warbling Vireo in Massachusetts is projected to stay roughly flat through 2030, near 3.3 (95% range 2.4–4.2). A 5-year backtest shows a typical error of ±8.1%, with 100% of held-out values landing inside the 95% band.19662030
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 →
20263.12.24.0
20273.12.34.0
20283.22.34.1
20293.22.44.1
20303.32.44.2

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 →
N. Andover820251995
Chesterfield720251973
Monterey720252019
Maynard620251972
E Pepperell619941966
Warren520091968
Warren 2520252010
Belchertown420251967
Prattville320191995
Newburyport320221967
S Barre320251971
Sheffield320221971
Hancock320151997
N Oxford220251968
Mansfield220251971
Princeton219761974
N Orange220251971
Pittsfield220091970
Cummington 2220252015
Marion120251992
Ware River120132012
Brockton120181994
Littleton120251967
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 2026-08-14.