The California thrasher (Toxostoma redivivum) is a medium-sized songbird found in chaparral and desert habitats throughout California and Baja California. With its long curved bill and brown speckled plumage, the California thrasher bears a resemblance to its cousin, the brown thrasher of the eastern United States. However, the California thrasher has paler plumage overall and darker streaking on the breast.
California thrashers are year-round residents across their range and do not migrate. They can be found in foothill canyons, arroyos, desert oases, scrubby flats, and chaparral-covered hillsides. Their habitat generally consists of dense, low vegetation interspersed with bare ground.
Range and Population
The California thrasher has a fairly restricted range within California, Baja California, and extreme western Arizona. Its total global population is estimated at 1.5 million birds. Within California, the species is considered fairly common throughout appropriate habitats.
Here is a map showing the range of the California thrasher:
Population densities vary across the range but may reach over 12 pairs per 40 hectares in optimal habitat. The species has a large range and is not currently considered threatened. However, localized declines have occurred in areas of heavy habitat loss and fragmentation.
Identification
The California thrasher is a medium-large songbird measuring 23-33 cm (9-13 inches) long with a wingspan of 30-36 cm (12-14 inches).
Distinctive identification features include:
- Rich brown upperparts with heavy black streaking
- Creamy white underparts with bold black spotting forming bars or chevrons
- Long curved bill with yellow base
- Yellow eyes
- Long tail often cocked upwards
The sexes are similar in appearance. Juveniles have less vivid patterning and a shorter bill. While foraging on the ground, the bird has a distinctive horizontal posture with cocked tail. In flight, the tail is typically held closed.
The California thrasher produces a wide variety of vocalizations including chucks, chats, whistles, and screeches. Its most famous call is an elaborate and melodious song with phrases repeated twice.
Behavior
The California thrasher spends much of its time walking or hopping along the ground, stopping frequently to probe the soil for food. It has an omnivorous diet consisting mainly of arthropods, small vertebrates, seeds, and fruit.
This species is territorial and mated pairs defend an area of around 4 hectares (10 acres). Both sexes sing, with males singing more frequently early in breeding season.
Nesting occurs from March to June with the female building a nest low in a shrub or tree. She lays 3-4 pale blue eggs which she incubates alone for 14 days. The male helps feed the young which leave the nest at 10-15 days old.
Threats and Conservation
The California thrasher adapts readily to human presence and commonly occurs in gardens and parks. However, large-scale habitat loss has caused declines in some areas. Major threats include:
- Urbanization and agricultural development
- Habitat degradation from invasive plants
- Fire suppression leading to dense overgrown habitat
- Predation from cats and other urban wildlife
Conservation actions that would benefit the species include:
- Protection of remaining habitat fragments
- Sensitive urban planning near wild areas
- Restoration of natural fire regimes
- Removal of invasive species
As a fairly common and resilient species, the California thrasher is not considered a conservation priority. However, it serves as an indicator of ecosystem health in arid Southwest habitats. Protecting adequate habitat for thrashers would benefit many other species with narrower ranges.
Frequently Asked Questions
How common are California thrashers?
California thrashers are considered fairly common within their habitat range in California and northern Baja California. Population densities can reach over 12 pairs per 40 hectares in optimal chaparral habitat. Overall populations are estimated at 1.5 million birds and are generally stable, though some local declines have occurred.
Where can I see a California thrasher?
Some good places to look for California thrashers include desert oases and riparian canyons in Anza-Borrego Desert State Park, coastal sage scrub and chaparral habitat in the Santa Monica Mountains, and arid canyonlands throughout the Mojave and Sonoran deserts. They readily visit backyards and parks with native vegetation.
What does a California thrasher sound like?
The song of the California thrasher is a melodious series of phrases repeated twice. It also gives chuck and chat alarm calls and a variety of other sounds. Listen for the repeating song coming from dense scrubby vegetation.
How can I attract California thrashers to my yard?
You can make your yard thrasher-friendly by planting native plants like manzanita, ceanothus, toyon, and desert willow. Leave patches of bare ground for foraging. Avoid trimming dense shrubs too severely. Provide water in a ground basin. Minimize use of pesticides.
Is the California thrasher endangered?
No, the California thrasher has a sufficiently large and widespread population that it is not considered threatened or endangered. However, habitat loss has caused declines in some areas, especially near urban development. The species would benefit from continued habitat protection and restoration.
California Thrasher Sightings by Region
Here are recent California thrasher sightings from citizen science databases:
Region | Number of Sightings |
---|---|
Southern California Coast | 612 |
Mojave Desert | 428 |
Central Valley | 301 |
San Francisco Bay Area | 201 |
Anza-Borrego Desert | 167 |
This table shows the California thrasher is most often reported along the southern California coast, followed by desert regions. Fewer sightings occur in the Central Valley and near San Francisco where habitat is less suitable. Anza-Borrego Desert also has many thrashers due to extensive surveys there.
Conclusion
In summary, the California thrasher is a bird of the chaparral and arid Southwest. With its curved bill and streaky brown plumage, this medium-sized songbird forages along the ground probing for invertebrates and seeds. Though not considered threatened, this species faces declines near areas of heavy urbanization and habitat destruction. Protecting large tracts of natural habitat will be key for the long-term viability of thrashers and other wildlife. Careful urban planning and restoration around parks and preserves can help sustain these birds even in close proximity to development.