BirdAnalyst
Species · BCR 34 · BBS 2026 Release · 1966–2025

Black-chinned Sparrow In Sierra Madre Occidental

All regionsSierra Madre OccidentalArid-land birds

Black-chinned Sparrow in Sierra Madre Occidental has declined: down 39% on the route-weighted index since 1976.

-39%Since 1976TrendPercent 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 →
18Routes 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 →
51YearsYears 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 Black-chinned Sparrow in Sierra Madre Occidental. See the full index history below.

Black-chinned Sparrow In Sierra Madre Occidental Population Forecast

If the recent trend holds, Black-chinned Sparrow in Sierra Madre Occidental is projected to fall about 23% by 2030 — from 1.1 in 2025 to a central estimate of 0.88 (95% range 0.00–2.0). A 5-year backtest shows a typical error of ±180.2%, with 100% of held-out values landing inside the 95% band.

-23%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 →
0.88Projected 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 →
0.00–2.095% 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 →
±180.2%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, Black-chinned Sparrow in Sierra Madre Occidental is projected to fall about 23% by 2030 — from 1.1 in 2025 to a central estimate of 0.88 (95% range 0.00–2.0). A 5-year backtest shows a typical error of ±180.2%, with 100% of held-out values landing inside the 95% band.19742030
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 →
20260.910.002.0
20270.910.002.0
20280.900.002.0
20290.890.002.0
20300.880.002.0

Routes In Sierra Madre Occidental

Routes recording Black-chinned Sparrow 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 →
Aztec PeakARIZONA171978
Tonto Vill.ARIZONA112025
CutterARIZONA72014
Emory PassNEW-MEXICO72025
Carr MtnARIZONA42025
Skull Valley 2ARIZONA42025
PrescottARIZONA22025
Skull ValleyARIZONA22024
RuckerARIZONA21999
PatagoniaARIZONA11987
WilliamsARIZONA12025
Bartlett ResARIZONA12024
SahuaritaARIZONA12019
PortalARIZONA12025
DragoonARIZONA11995
ReserveNEW-MEXICO12001
Vicks PeakNEW-MEXICO12025
MagdalenaNEW-MEXICO12018

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