BirdAnalyst
Species · BBS 2026 Release · 1966–2025

Gray Vireo Population Analysis

VireonidaeForest birdsVireo vicinior

Gray Vireo has surged: up 397% on the route-weighted index since 1970.

+397%Since 1970TrendPercent 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 →
141RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57Years 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 Gray Vireo

The Gray Vireo (Vireo vicinior) 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 141 Breeding Bird Survey routes across 7 states, most concentrated in the Southern Rockies / Colorado Plateau.
Family
Vireonidae · Forest birds

Notable Gray 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 →

No notable trend signals for Gray Vireo. See the full index history below.

Gray Vireo Population Forecast

If the recent trend holds, Gray Vireo is projected to rise about 25% by 2030 — from 0.06 in 2025 to a central estimate of 0.07 (95% range 0.05–0.09). A 5-year backtest shows a typical error of ±26.7%, with 80% of held-out values landing inside the 95% band.

+25%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 →
0.07Projected 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 →
0.05–0.0995% 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 →
±26.7%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, Gray Vireo is projected to rise about 25% by 2030 — from 0.06 in 2025 to a central estimate of 0.07 (95% range 0.05–0.09). A 5-year backtest shows a typical error of ±26.7%, with 80% of held-out values landing inside the 95% band.19682030
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 →
20260.070.040.09
20270.070.050.09
20280.070.050.09
20290.070.050.09
20300.070.050.09

Where the Gray Vireo Is Detected

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

Gray Vireo Population Trend by State

Gray 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 →
Arizona+12%197025
California-83%19793
Colorado+323%197625
Nevada+61%19984
New Mexico+137%197725
Texas+72%199012
Utah+13%197447

Gray Vireo Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Gray 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 →
Great Basin+272%199810
Southern Rockies / Colorado Plateau+90%197087
Sierra Madre Occidental-23%197517
Chihuahuan Desert+123%199414

Gray Vireo Conservation Status

Our route-weighted index shows it up about 397% since 1970.

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