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

Bell's Vireo Population Trend in Wisconsin

All statesForest birds

Bell's Vireo in Wisconsin has declined: down 39% on the route-weighted index since 1971.

-39%Since 1971TrendPercent 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 →
16Routes 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 →
29YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Bell's Vireo Trends in WisconsinNotable 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 Bell's Vireo in Wisconsin. See the full index history below.

Bell's Vireo Population Forecast in Wisconsin

If the recent trend holds, Bell's Vireo in Wisconsin is projected to stay roughly flat through 2028, near 0.02 (95% range 0.00–0.03). A 5-year backtest shows a typical error of ±33.5%, with 100% of held-out values landing inside the 95% band.

n/aChange by 2028TrendPercent 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 →
0.02Projected 2028 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
0.00–0.0395% 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 →
±33.5%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, Bell's Vireo in Wisconsin is projected to stay roughly flat through 2028, near 0.02 (95% range 0.00–0.03). A 5-year backtest shows a typical error of ±33.5%, with 100% of held-out values landing inside the 95% band.19662028
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 →
20240.020.000.03
20250.020.000.03
20260.020.000.03
20270.020.000.03
20280.020.000.03

Bell's Vireo Survey Routes in Wisconsin

Routes recording Bell's Vireo in Wisconsin.
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 →
Trempealeau220111972
Annaton220232014
N Andover120182018
Gilmanton120072007
Wiota119971966
Hebron120132013
Beloit120102010
Mather119741973
Verona120152015
Clintonville119961996
Newburg Crns120151966
Viroqua119821982
Rolling Grnd119901980
Pardeeville119941994
Fall River120172017
Highland119991999

Bell's Vireo Population Trend in Other States

arizonaarkansascaliforniacoloradoillinoisindianaiowakansaskentuckymichiganminnesotamissourinebraskanevadanew-mexiconorth-dakotaohiooklahomasouth-dakotatexasutah

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