BirdAnalyst
Guild · California · BBS 2025 Release · 1966–2024

Arid-land Birds In California

All statesCalifornia

10 species in this guild. As a group they are -69%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 fallen sharply in California, down 69% since 1970.

Arid-land Birds In California Population Forecast

If the recent trend holds, Arid-land birds in California is projected to fall about 22% by 2029 — from 0.68 in 2024 to a central estimate of 0.53 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±9.9%, with 100% of held-out values landing inside the 95% band.

-22%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 →
0.53Projected 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 →
0.00–1.495% 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 →
±9.9%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, Arid-land birds in California is projected to fall about 22% by 2029 — from 0.68 in 2024 to a central estimate of 0.53 (95% range 0.00–1.4). A 5-year backtest shows a typical error of ±9.9%, 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 →
20250.580.001.4
20260.570.001.4
20270.560.001.4
20280.540.001.4
20290.530.001.4

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 →
Cactus WrenTroglodytidae-82%
Greater RoadrunnerCuculidae-80%
Black-tailed GnatcatcherPolioptilidae-74%
VerdinRemizidae-66%
Gambel's QuailOdontophoridae-66%
Black-throated SparrowPasserellidae-59%
PhainopeplaPtiliogonatidae+17%
Abert's TowheePasserellidae+57%
Lucy's WarblerParulidae+101%
Gila WoodpeckerPicidae+144%

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