BirdAnalyst
Species · BCR 34 · BBS 2025 Release · 1966–2024

Bell's Vireo In Sierra Madre Occidental

All regionsSierra Madre OccidentalForest birds

Bell's Vireo in Sierra Madre Occidental has edged down: down 18% on the route-weighted index since 1970.

-18%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 →
20Routes 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 →
56YearsYears 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 Bell's Vireo in Sierra Madre Occidental. See the full index history below.

Forecast

If the recent trend holds, Bell's Vireo in Sierra Madre Occidental is projected to fall about 23% by 2029 — from 7.8 in 2024 to a central estimate of 6.0 (95% range 2.1–10.0). A 5-year backtest shows a typical error of ±25.9%, with 100% of held-out values landing inside the 95% band.

-23%Change by 2029TrendPercent 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 →
6.0Projected 2029 indexProjected indexThe central forecast of the abundance index if the recent trend continues. A projection of the current trajectory, not a prediction.Full methodology →
2.1–10.095% 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 →
±25.9%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 Sierra Madre Occidental is projected to fall about 23% by 2029 — from 7.8 in 2024 to a central estimate of 6.0 (95% range 2.1–10.0). A 5-year backtest shows a typical error of ±25.9%, with 100% of held-out values landing inside the 95% band.19682029
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 →
20255.92.09.9
20265.92.09.9
20276.02.09.9
20286.02.09.9
20296.02.110.0

Routes In Sierra Madre Occidental

Routes recording Bell's Vireo in Sierra Madre Occidental.
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 →
PomereneARIZONA912024
AmadoARIZONA222023
Carr MtnARIZONA172024
RedingtonARIZONA142023
CutterARIZONA132014
SunizonaARIZONA81997
Bartlett ResARIZONA72024
Peña BlancaARIZONA62024
PatagoniaARIZONA62024
SahuaritaARIZONA42024
Skull ValleyARIZONA32024
San SimonARIZONA22024
McnealARIZONA22024
Mormon LakeARIZONA11968
Aztec PeakARIZONA11976
PortalARIZONA12024
Sunizona 2ARIZONA12024
DragoonARIZONA12001
RuckerARIZONA11999
Emory PassNEW-MEXICO11998

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