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Species · Idaho · BBS 2026 Release · 1966–2025

Cassin's Vireo Population Trend in Idaho

All statesForest birds

Cassin's Vireo in Idaho has surged: up 187% on the route-weighted index since 1973.

+187%Since 1973TrendPercent 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 →
27Routes 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 →
53YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Cassin's Vireo Trends in IdahoNotable 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 →

Cassin's Vireo has surged in Idaho: up 187% on the route-weighted index since 1973.

Cassin's Vireo Population Forecast in Idaho

If the recent trend holds, Cassin's Vireo in Idaho is projected to stay roughly flat through 2030, near 1.6 (95% range 0.88–2.2). A 5-year backtest shows a typical error of ±12.7%, with 100% of held-out values landing inside the 95% band.

+3%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 →
1.6Projected 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 →
0.88–2.295% 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 →
±12.7%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, Cassin's Vireo in Idaho is projected to stay roughly flat through 2030, near 1.6 (95% range 0.88–2.2). A 5-year backtest shows a typical error of ±12.7%, with 100% of held-out values landing inside the 95% band.19692030
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 →
20261.50.802.2
20271.50.822.2
20281.50.842.2
20291.50.862.2
20301.60.882.2

Cassin's Vireo Survey Routes in Idaho

Routes recording Cassin's Vireo in Idaho.
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 →
Mivoden1520251977
Coolin1320251986
Lolo Pass620191992
Grangeville520251986
Rochat Divde520251993
Pierce520071992
Naples420251972
N Fork Cda R420191993
Nezperce Nf419991992
Avery320251982
Marble Creek320251988
Nezperce220121985
Golden220161993
Centerville220252001
Magic Mtn220012001
Featherville220251997
Cabarton220241998
Gifford120171973
Baker120242024
Alturas119691969
Baldy Mountain120162013
Joel120191990
Salmon River120251989
Burgdorf120131996
Yellow Pine120072001

Cassin's Vireo Population Trend in Other States

alaskacaliforniamontanaoregonwashington

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.