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

Gray Vireo In Sierra Madre Occidental

All regionsSierra Madre OccidentalForest birds

Gray Vireo in Sierra Madre Occidental has edged down: down 11% on the route-weighted index since 1975.

-11%Since 1975TrendPercent 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 RegionSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
43YearsYears 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 Gray Vireo in Sierra Madre Occidental. See the full index history below.

Gray Vireo In Sierra Madre Occidental Population Forecast

If the recent trend holds, Gray Vireo in Sierra Madre Occidental is projected to fall about 28% by 2029 — from 1.0 in 2024 to a central estimate of 0.72 (95% range 0.05–1.4). A 5-year backtest shows a typical error of ±99.3%, with 100% of held-out values landing inside the 95% band.

-28%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 →
0.72Projected 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 →
0.05–1.495% 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 →
±99.3%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 in Sierra Madre Occidental is projected to fall about 28% by 2029 — from 1.0 in 2024 to a central estimate of 0.72 (95% range 0.05–1.4). A 5-year backtest shows a typical error of ±99.3%, 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 →
20250.710.031.4
20260.710.041.4
20270.710.041.4
20280.720.051.4
20290.720.051.4

Routes In Sierra Madre Occidental

Routes recording Gray 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 →
Carr MtnARIZONA82024
MagdalenaNEW-MEXICO52024
Mormon LakeARIZONA41968
Forest LakesARIZONA42024
Aztec PeakARIZONA31978
CutterARIZONA31996
RedingtonARIZONA32022
Tonto Vill.ARIZONA22021
BlueARIZONA11984
MaineARIZONA11997
Skull ValleyARIZONA12024
Bartlett ResARIZONA12019
Clay SpringARIZONA12010
ReserveNEW-MEXICO12022
Vicks PeakNEW-MEXICO12022
Emory PassNEW-MEXICO12012

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