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Species · Arizona · BBS 2025 Release · 1966–2024

Cassin's Sparrow Population Trend in Arizona

All statesGrassland birds

Cassin's Sparrow in Arizona has fallen sharply: down 64% on the route-weighted index since 1971.

-64%Since 1971TrendPercent 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 →
15Routes 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 →
37YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Cassin's Sparrow 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 declinecomputed 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 →

Cassin's Sparrow has fallen sharply in Arizona: down 64% on the route-weighted index since 1971.

Cassin's Sparrow Population Forecast in Arizona

If the recent trend holds, Cassin's Sparrow in Arizona is projected to fall about 62% by 2029 — from 0.49 in 2024 to a central estimate of 0.18 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±181.9%, with 100% of held-out values landing inside the 95% band.

-62%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 →
0.18Projected 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 →
0.00–1.195% 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 →
±181.9%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, Cassin's Sparrow in Arizona is projected to fall about 62% by 2029 — from 0.49 in 2024 to a central estimate of 0.18 (95% range 0.00–1.1). A 5-year backtest shows a typical error of ±181.9%, 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 →
20250.220.001.2
20260.210.001.1
20270.200.001.1
20280.190.001.1
20290.180.001.1

Cassin's Sparrow Survey Routes in Arizona

Routes recording Cassin's Sparrow 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 →
Sunizona 21720242001
Mcneal1520191993
Sunizona819921968
Cactus Forest319911991
San Simon320191983
Rucker219981993
Patagonia120011973
The Gap119711971
Dragoon120071993
Amado120221994
Sahuarita120231993
Clay Spring120112011
Carr Mtn120082008
Pomerene120212021
Peña Blanca119931979

Cassin's Sparrow Population Trend in Other States

arkansascaliforniacoloradokansasnebraskanew-mexicooklahomatexaswyoming

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