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

Black-headed Grosbeak In Sierra Madre Occidental

All regionsSierra Madre OccidentalGeneralists

Black-headed Grosbeak in Sierra Madre Occidental has risen sharply: up 61% on the route-weighted index since 1970.

+61%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 →
33Routes 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 →

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 →

Black-headed Grosbeak has risen sharply in Sierra Madre Occidental: up 61% on the route-weighted index since 1970.

Forecast

If the recent trend holds, Black-headed Grosbeak in Sierra Madre Occidental is projected to rise about 35% by 2029 — from 3.9 in 2024 to a central estimate of 5.2 (95% range 1.1–9.4). A 5-year backtest shows a typical error of ±16.3%, with 100% of held-out values landing inside the 95% band.

+35%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 →
5.2Projected 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 →
1.1–9.495% 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 →
±16.3%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, Black-headed Grosbeak in Sierra Madre Occidental is projected to rise about 35% by 2029 — from 3.9 in 2024 to a central estimate of 5.2 (95% range 1.1–9.4). A 5-year backtest shows a typical error of ±16.3%, 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 →
20255.31.29.5
20265.31.29.5
20275.31.19.4
20285.31.19.4
20295.21.19.4

Routes In Sierra Madre Occidental

Routes recording Black-headed Grosbeak 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 →
PortalARIZONA202024
Peña BlancaARIZONA172024
Aztec PeakARIZONA131978
Mt. GrahamARIZONA132023
PrescottARIZONA122022
FlagstaffARIZONA112022
SprucedaleARIZONA102023
Forest LakesARIZONA82024
PinetopARIZONA62022
RuckerARIZONA62009
Emory PassNEW-MEXICO62024
PatagoniaARIZONA52024
WilliamsARIZONA52019
RedingtonARIZONA52023
DragoonARIZONA52009
Mormon LakeARIZONA41975
CutterARIZONA42014
ReserveNEW-MEXICO42023
PomereneARIZONA32024
SunizonaARIZONA31997
Carr MtnARIZONA32024
BlueARIZONA21990
Skull ValleyARIZONA22024
AmadoARIZONA22021
MaineARIZONA12024

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