California Thrasher

Overview

The California thrasher (Toxostoma redivivum) is the largest member of the thrasher family, Mimidae, and is found primarily in chaparral habitats across California and northern Baja California. It is classified as a species of Least Concern by the IUCN, though it faces threats from habitat fragmentation and climate change.

Identification

• Measures approximately 32 cm (13 in) in length and can weigh up to 90 g (3.2 oz), making it the largest thrasher species.
• Features deep grayish-brown upperparts with olive tones on the tail, and underparts that are buffy to tawny brown with smoky gray upper breast and flanks.
• Possesses a distinctive long, decurved bill and a long tail, along with a grayish buff supercilium and dark cheek pattern and eye line.
• Unusually for thrashers, it has dark eyes and is known for its exuberant, mimicking song.

Habitat

This species is a year-round resident of the California Coast Ranges and the western slope of the Sierra Nevada, primarily inhabiting chaparral but also using sagebrush, juniper bushland, and dense oak woodlands. Its range extends from Santa Cruz and Placer counties in California south into northwestern Baja California, Mexico, with a secondary population in northern California. It is rarely found in the Central Valley and can occasionally be seen in suburban parks with dense cover.

Diet

The California thrasher forages mostly on the ground, digging and sweeping leaf litter and soil with its bill to find food. Its diet in spring is almost exclusively insects and small invertebrates, to which it adds small soft fruits during the rest of the year. Approximately two-thirds of its foraging activity takes place beneath dense and continuous cover.

Did you know?

The species is considered highly vulnerable to climate change, with models predicting a 66% loss of its current breeding range under a 3.0 °C warming scenario due to increased wildfire risks. It also exhibits notable sensitivity to song syntax, reacting differently to variations in song structure, which plays a crucial role in territorial defence.