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Species · California · BBS 2025 Release · 1966–2024

Abert's Towhee Population Trend in California

All statesArid-land birds

Abert's Towhee in California has risen sharply: up 57% on the route-weighted index since 1974.

+57%Since 1974TrendPercent 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 →
10Routes 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 →
51YearsYears surveyedNumber of years with at least one standard-protocol run in this geography. A longer record makes the trend more reliable.Full methodology →

Notable Abert's Towhee Trends in CaliforniaNotable 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 increasecomputed 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 →

Abert's Towhee has risen sharply in California: up 57% on the route-weighted index since 1974.

Abert's Towhee Population Forecast in California

If the recent trend holds, Abert's Towhee in California is projected to fall about 32% by 2029 — from 0.11 in 2024 to a central estimate of 0.07 (95% range 0.00–0.17). A 5-year backtest shows a typical error of ±32.3%, with 100% of held-out values landing inside the 95% band.

-32%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 →
0.07Projected 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 →
0.00–0.1795% 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 →
±32.3%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, Abert's Towhee in California is projected to fall about 32% by 2029 — from 0.11 in 2024 to a central estimate of 0.07 (95% range 0.00–0.17). A 5-year backtest shows a typical error of ±32.3%, 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 →
20250.070.000.17
20260.070.000.17
20270.070.000.17
20280.070.000.17
20290.070.000.17

Abert's Towhee Survey Routes in California

Routes recording Abert's Towhee in California.
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 →
Niland1020241979
Brawley920011976
Parker Dam620071973
Coachella Cn420002000
Blythe419791979
Imperial Dam320061973
Glamis220171968
Havasu Lake220031973
Palo Verde120231973
Alamo River119911973

Abert's Towhee Population Trend in Other States

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