BirdAnalyst
Species · BCR 10 · BBS 2026 Release · 1966–2025

Cassin's Vireo In Northern Rockies

All regionsNorthern RockiesForest birds

Cassin's Vireo in Northern Rockies has edged down: down 22% on the route-weighted index since 1970.

-22%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 →
98Routes In RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable SignalsNotable 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 Cassin's Vireo in Northern Rockies. See the full index history below.

Cassin's Vireo In Northern Rockies Population Forecast

If the recent trend holds, Cassin's Vireo in Northern Rockies is projected to stay roughly flat through 2030, near 1.8 (95% range 0.95–2.6). A 5-year backtest shows a typical error of ±7.8%, with 100% of held-out values landing inside the 95% band.

+7%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 →
1.8Projected 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 →
0.95–2.695% 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 →
±7.8%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 Northern Rockies is projected to stay roughly flat through 2030, near 1.8 (95% range 0.95–2.6). A 5-year backtest shows a typical error of ±7.8%, with 100% 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 →
20261.70.922.5
20271.70.922.5
20281.70.932.6
20291.80.942.6
20301.80.952.6

Routes In Northern Rockies

Routes recording Cassin's Vireo in Northern Rockies.
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 →
Pagil GulchMONTANA222025
CusickWASHINGTON222025
Fish CreekMONTANA182024
MivodenIDAHO152025
WallowaOREGON152025
Omak CreekWASHINGTON142024
CoolinIDAHO132025
FloraOREGON122023
NoxonMONTANA112023
Hells CanyonOREGON112025
Deer ParkWASHINGTON102015
Hash RockOREGON92025
NewbridgeOREGON92025
Twin LakesWASHINGTON92025
Sullivan LkWASHINGTON91999
TroyOREGON82025
UnityOREGON82025
Skalkho-RyeMONTANA72022
Whitefish LakeMONTANA72024
Spring LakeWASHINGTON72025
Lolo PassIDAHO62019
St RegisMONTANA62025
Silver CreekOREGON62025
GrangevilleIDAHO52025
PierceIDAHO52007

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