BirdAnalyst
Species · BBS 2026 Release · 1966–2025

Warbling Vireo Population Analysis

VireonidaeForest birdsVireo gilvus

Warbling Vireo 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 →
2,554RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
59Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Warbling Vireo

The Warbling Vireo (Vireo gilvus) is a North American member of the Vireos (Vireonidae). In this analysis it is grouped with the forest birds.

Size
4.5–6 in long (11–15 cm) — a small, deliberate songbird (typical for the family)
Habitat
Woodlands and forest edges, including wooded suburbs and parks.
Diet
Insects and spiders gleaned from foliage and bark, with seeds and berries in season.
Range
Recorded on 2,554 Breeding Bird Survey routes across 46 states, most concentrated in the Eastern Tallgrass Prairie.
Family
Vireonidae · Forest birds

Notable Warbling Vireo TrendsNotable 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 surveyed states: up 187% on the route-weighted index since 1968.

Warbling Vireo Population Forecast

If the recent trend holds, Warbling Vireo is projected to stay roughly flat through 2030, near 3.6 (95% range 3.2–4.1). A 5-year backtest shows a typical error of ±6%, 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 →
3.6Projected 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 →
3.2–4.195% 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 →
±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, Warbling Vireo is projected to stay roughly flat through 2030, near 3.6 (95% range 3.2–4.1). A 5-year backtest shows a typical error of ±6%, 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 →
20263.53.03.9
20273.53.13.9
20283.53.14.0
20293.63.14.0
20303.63.24.1

Where the Warbling Vireo Is Detected

BBS routes recording Warbling Vireo, sized by most recent count.

Warbling Vireo Population Trend by State

Warbling Vireo population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Alabamainsufficient datan/a6
Alaska+551%199311
Arizona13×197429
Arkansas+220%196932
California+34%1970182
Colorado+353%1970111
Connecticut+205%196820
Delaware-44%19718
Idaho+165%197256
Illinois+175%1968104
Indiana+89%196868
Iowa+209%196939
Kansas+155%196964
Kentucky+171%196846
Louisiana-48%197010
Maine+157%196965
Maryland+168%196847
Massachusetts+573%196828
Michigan+13%196897
Minnesota+19%196985
Mississippi-41%196913
Missouri+12%196981
Montana+119%197083
Nebraska+213%196966
Nevada-18%197926
New Hampshire+22%196825
New Jersey12×196825
New Mexico+244%197031
New York+331%1968123
North Carolina-36%199711
North Dakota+259%196950
Ohio-4%196888
Oklahoma+21%196950
Oregon+69%1970116
Pennsylvania+207%1968114
Rhode Island+356%19894
South Dakota+255%196957
Tennessee+470%196828
Texas-71%197119
Utah+865%197265
Vermont+82%196826
Virginia+103%196933
Washington+114%197088
West Virginia-76%196853
Wisconsin-14%196895
Wyoming+65%197076

Warbling Vireo Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Warbling Vireo population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Northern Pacific Rainforest+12%1970138
Great Basin+213%1970149
Northern Rockies+91%1970194
Prairie Potholes+296%1969112
Boreal Hardwood Transition-73%1968106
Lower Great Lakes / St. Lawrence Plain+225%196885
Atlantic Northern Forest+92%1968139
Sierra Nevada+94%197140
Southern Rockies / Colorado Plateau+424%1970169
Badlands and Prairies+75%196981
Shortgrass Prairie+94%197341
Central Mixed Grass Prairie+173%196996
Oaks and Prairies-32%197016
Eastern Tallgrass Prairie+163%1968273
Prairie Hardwood Transition+19%1968160
Central Hardwoods+146%1968130
West Gulf Coastal Plain / Ouachitas+11%197038
Mississippi Alluvial Valley+11%196825
Southeastern Coastal Plain+7%196927
Appalachian Mountains+7%1968256
Piedmont+164%196857
New England / Mid-Atlantic Coast+225%196896
Coastal California+113%197079
Sonoran and Mojave Deserts-51%19809
Sierra Madre Occidental+186%197427
Chihuahuan Desert+76%19828

Warbling Vireo Conservation Status

Our route-weighted index shows it up about 187% since 1968.

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14. Trend is a route-weighted relative-abundance index, not an absolute population.