BirdAnalyst
Species · BCR 33 · BBS 2025 Release · 1966–2024

Black-chinned Sparrow In Sonoran and Mojave Deserts

All regionsSonoran and Mojave DesertsGeneralists

Black-chinned Sparrow in Sonoran and Mojave Deserts has fallen sharply: down 63% on the route-weighted index since 1973.

-63%Since 1973TrendPercent 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 →
8Routes 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 →
22YearsYears 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 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 Sonoran and Mojave Deserts: down 63% on the route-weighted index since 1973.

Forecast

If the recent trend holds, Black-chinned Sparrow in Sonoran and Mojave Deserts is projected to fall about 39% by 2029 — from 0.07 in 2024 to a central estimate of 0.04 (95% range 0.00–0.14). A 5-year backtest shows a typical error of ±50.5%, with 100% of held-out values landing inside the 95% band.

-39%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 →
0.04Projected 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 →
0.00–0.1495% 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 →
±50.5%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-chinned Sparrow in Sonoran and Mojave Deserts is projected to fall about 39% by 2029 — from 0.07 in 2024 to a central estimate of 0.04 (95% range 0.00–0.14). A 5-year backtest shows a typical error of ±50.5%, 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 →
20250.040.000.14
20260.040.000.14
20270.040.000.14
20280.040.000.14
20290.040.000.14

Routes In Sonoran and Mojave Deserts

Routes recording Black-chinned Sparrow in Sonoran and Mojave Deserts.
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 →
NelsonNEVADA52010
Cholla Gard.CALIFORNIA32001
BarstowCALIFORNIA21968
Coachella CnCALIFORNIA21973
PearblossomCALIFORNIA22024
OnyxCALIFORNIA11996
Kelso ValleyCALIFORNIA11990
Joshua TreeCALIFORNIA11973

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