BirdAnalyst
Guild · California · BBS 2026 Release · 1966–2025

Arid-land Birds In California

All statesCalifornia

20 species in this guild. As a group they are -43%Guild trendA mean-index aggregate across the species in this group — the structural direction of the guild, with individual-species noise smoothed out.Full methodology → since 1970.

Guild SignalsNotable signalsLong-arc shifts the engine flags automatically — sustained declines or increases large enough to stand out from year-to-year noise.Full methodology →

guild collapsecomputed 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 →

Arid-land birds as a group have declined in California, down 43% since 1970.

Arid-land Birds In California Population Forecast

If the recent trend holds, Arid-land birds in California is projected to fall about 32% by 2030 — from 1.4 in 2025 to a central estimate of 0.94 (95% range 0.32–1.6). A 5-year backtest shows a typical error of ±28.4%, with 100% of held-out values landing inside the 95% band.

-32%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 →
0.94Projected 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 →
0.32–1.695% 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 →
±28.4%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, Arid-land birds in California is projected to fall about 32% by 2030 — from 1.4 in 2025 to a central estimate of 0.94 (95% range 0.32–1.6). A 5-year backtest shows a typical error of ±28.4%, 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 →
20260.970.351.6
20270.960.341.6
20280.950.341.6
20290.940.331.6
20300.940.321.6

Member Species In California

Arid-land birds species in California.
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 →
LeConte's ThrasherMimidae-97%
Bendire's ThrasherMimidae-88%
Greater RoadrunnerCuculidae-79%
Cactus WrenTroglodytidae-76%
Black-tailed GnatcatcherPolioptilidae-73%
Black-chinned SparrowPasserellidae-69%
Black-throated SparrowPasserellidae-54%
VerdinRemizidae-54%
Sagebrush SparrowPasserellidae-43%
Bell's SparrowPasserellidae-15%
PhainopeplaPtiliogonatidae-15%
California TowheePasserellidae-4%
Crissal ThrasherMimidae+0%
California ThrasherMimidae+3%
Abert's TowheePasserellidae+48%
Lucy's WarblerParulidae+101%
Gila WoodpeckerPicidae+144%
Brewer's SparrowPasserellidae+163%
Sage ThrasherMimidae+298%
Rufous-crowned SparrowPasserellidae+382%

Source: USGS North American Breeding Bird Survey, retrieved 2026-08-14.