BirdAnalyst
Species · Arizona · BBS 2025 Release · 1966–2024

Black-headed Grosbeak Population Trend in Arizona

All statesGeneralists

Black-headed Grosbeak in Arizona has surged: up 82% on the route-weighted index since 1970.

+82%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 →
44Routes In StateSurvey 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 Black-headed Grosbeak Trends in ArizonaNotable 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 surged in Arizona: up 82% on the route-weighted index since 1970.

Black-headed Grosbeak Population Forecast in Arizona

If the recent trend holds, Black-headed Grosbeak in Arizona is projected to rise about 13% by 2029 — from 2.1 in 2024 to a central estimate of 2.4 (95% range 0.20–4.6). A 5-year backtest shows a typical error of ±12.5%, with 100% of held-out values landing inside the 95% band.

+13%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 →
2.4Projected 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 →
0.20–4.695% 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 →
±12.5%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 Arizona is projected to rise about 13% by 2029 — from 2.1 in 2024 to a central estimate of 2.4 (95% range 0.20–4.6). A 5-year backtest shows a typical error of ±12.5%, 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 →
20252.50.264.7
20262.50.254.7
20272.40.234.7
20282.40.214.7
20292.40.204.6

Black-headed Grosbeak Survey Routes in Arizona

Routes recording Black-headed Grosbeak in Arizona.
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 →
Portal2020241975
Peña Blanca1720241977
Aztec Peak1319781974
Mt. Graham1320231995
Prescott1220221974
Flagstaff1120221988
Zeniff1019731968
Tsaile1020231995
Sprucedale1020231992
Dry Park920241992
Forest Lakes820241994
Rucker620091993
Pinetop620221993
Dragoon520091993
Patagonia520241968
Williams520191999
Redington520231999
Mormon Lake419751968
Cutter420142014
Yampai319711971
Hunt319761976
Pomerene320241974
Sunizona319971968
Carr Mtn320241985
The Gap219751975

Black-headed Grosbeak Population Trend in Other States

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