BirdAnalyst
Species · BBS 2026 Release · 1966–2025

Black-chinned Sparrow Population Analysis

PasserellidaeArid-land birdsSpizella atrogularis

Black-chinned Sparrow has fallen sharply: down 58% on the route-weighted index since 1970.

-58%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 →
112RoutesSurvey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
57Years SurveyedYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

About the Black-chinned Sparrow

The Black-chinned Sparrow (Spizella atrogularis) is a North American member of the New World Sparrows (Passerellidae). In this analysis it is grouped with the arid-land birds.

Size
4.5–7.5 in long (12–19 cm) — a small songbird (typical for the family)
Habitat
Deserts, dry scrub and brushland of the Southwest.
Diet
Seeds, insects and cactus fruit of arid-land plants.
Range
Recorded on 112 Breeding Bird Survey routes across 7 states, most concentrated in the Coastal California.
Family
Passerellidae · Arid-land birds

Notable Black-chinned Sparrow TrendsNotable 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 →

Black-chinned Sparrow has fallen sharply in surveyed states: down 58% on the route-weighted index since 1970.

Black-chinned Sparrow Population Forecast

If the recent trend holds, Black-chinned Sparrow is projected to fall about 71% by 2030 — from 0.05 in 2025 to a central estimate of 0.01 (95% range 0.00–0.12). A 5-year backtest shows a typical error of ±60.4%, with 100% of held-out values landing inside the 95% band.

-71%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 →
0.01Projected 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 →
0.00–0.1295% 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 →
±60.4%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 is projected to fall about 71% by 2030 — from 0.05 in 2025 to a central estimate of 0.01 (95% range 0.00–0.12). A 5-year backtest shows a typical error of ±60.4%, with 100% of held-out values landing inside the 95% band.19682030
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 →
20260.020.000.13
20270.020.000.12
20280.020.000.12
20290.020.000.12
20300.010.000.12

Where the Black-chinned Sparrow Is Detected

BBS routes recording Black-chinned Sparrow, sized by most recent count.

Black-chinned Sparrow Population Trend by State

Black-chinned Sparrow population trend by state.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Arizona-49%197418
California-69%197060
Coloradoinsufficient datan/a1
Nevada-42%19984
New Mexico-1%197818
Texas-32%19955
Utah-89%19966

Black-chinned Sparrow Population Trend by Region

Bird Conservation Regions are the ecological unit for trends.

Black-chinned Sparrow population trend by Bird Conservation Region.
TrendPercent 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 →Baseline yearThe first year of the smoothed window the trend is measured from. An earlier baseline means a longer record stands behind the number.Full methodology →Survey routesHow many standard-protocol BBS routes contributed counts. More routes means a steadier, better-sampled index; very thin coverage is suppressed.Full methodology →
Great Basin+45%19966
Southern Rockies / Colorado Plateau-78%197316
Coastal California-78%197144
Sonoran and Mojave Deserts-48%19738
Sierra Madre Occidental-39%197618
Chihuahuan Desert-18%197811

Black-chinned Sparrow Conservation Status

Our route-weighted index shows it down about 58% since 1970.

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14. Trend is a route-weighted relative-abundance index, not an absolute population.