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

Warbling Vireo Population Trend in Connecticut

All statesForest birds

Warbling Vireo in Connecticut has surged: up 187% on the route-weighted index since 1968.

+187%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 →
20Routes 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 ConnecticutNotable 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 Connecticut: up 187% on the route-weighted index since 1968.

Warbling Vireo Population Forecast in Connecticut

If the recent trend holds, Warbling Vireo in Connecticut is projected to rise about 60% by 2029 — from 3.0 in 2024 to a central estimate of 4.8 (95% range 3.2–6.4). A 5-year backtest shows a typical error of ±54.2%, with 20% of held-out values landing inside the 95% band.

+60%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 →
4.8Projected 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 →
3.2–6.495% 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 →
±54.2%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, Warbling Vireo in Connecticut is projected to rise about 60% by 2029 — from 3.0 in 2024 to a central estimate of 4.8 (95% range 3.2–6.4). A 5-year backtest shows a typical error of ±54.2%, with 20% 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 →
20254.62.96.2
20264.63.06.3
20274.73.16.3
20284.73.16.4
20294.83.26.4

Warbling Vireo Survey Routes in Connecticut

Routes recording Warbling Vireo in Connecticut.
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 →
E Hartland1319921966
Long Hill1120191974
Willimantic920181977
Sherman620191973
Mid Haddam620241991
Woodstock 2620242017
Greenwich520181972
Granby520241989
Southington420241973
Uncasville320241977
Woodstock220071970
Westbrook220241980
Danbury220231971
Warren220111972
New Hartford219871972
New Hartford220221994
Mystic120231981
Buckingham120221967
No Woodbury120211967
Warren 2120242018

Warbling Vireo Population Trend in Other States

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

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