LeConte's thrasher

LeConte's thrasher (''Toxostoma lecontei'') is a pale bird found in the southwestern United States and northwestern Mexico. It prefers to live in deserts with very little vegetation, where it blends in with the sandy soils. LeConte's thrashers are nonmigratory birds that reside in the same territory annually. Although the species has been decreasing in certain areas of its range, in particular California, it still is abundant enough to not be considered for vulnerable status.

These birds are terrestrial and only fly occasionally. Both sexes are heavily involved in the nest building, incubating, and brooding process, though each alternates with primary responsibility of the tasks. LeConte's thrashers frequently compete with species such as the northern mockingbird, loggerhead shrike and greater roadrunner, as well as being potential prey for the latter.

Taxonomy

LeConte's thrasher is named after Dr. John Lawrence LeConte, an entomologist who eventually became president of the American Association for the Advancement of Science. There are two subspecies:

''T.l. lecontei'' (Lawrence, 1851) – range is from southwestern United States (south central and eastern California, southwest Utah, and south central Arizona) to northwestern Mexico (north east Baja California and northwest Sonora).

''T.l. arenicola'' (Anthony, 1897) Rosalia thrasher; west coast of Baja California.

''T.l. arenicola'' has been proposed by the American Ornithologists Union as separate species, and treated as a separate species by other authors. and a name of Vizcaino thrasher if it becomes official. ''T.l. arenicola'' still is treated as a subspecies of ''lecontei'' by some authors, however. A proposed race ''T.c. macmillanorum'' only exhibits minor differences in plumage from ''T.l. lecontei'' (such as a darker crown and lighter flanks), but is not justified by biochemical or morphological grounds. One study suggested that the phylogeographic structure of the LeConte's is consistent with both its geographic distribution and genetics, with the Vizcaíno Desert in Baja California acting as a barrier initiating allopatric speciation.

The two closest living relatives of LeConte's thrasher, the California thrasher and the crissal thrasher, form as the ''lecontei'' group. The similarities with these three species contrasted with other ''Toxostoma'' thrashers, in particular the sickle-shaped bill, longer legs and smaller wings indicated its adaption to a preference to running and digging for food.

Description

LeConte's thrasher weighs from and are , and there is no sexual dimorphism within the species. Their wings are typical of birds that are sedentary, as they are short and rounded. There are noted differences among the subspecies. The crown, back, shoulders, and rump of ''T.c. lecontei'' possess a sandy pale-gray color. The primaries and secondaries are grayish brown. The rectrices are of a darker gray brown that contrasts with the plumage. Lores and ear-coverts are a mottled gray brown. The throat is an off-whitish color of a darker stripe. The chest and belly is puffy gray, and the vent and uppertail coverts are of a warmer tint in contrast to the palish chest and belly. The underwing is both gray and buff, with a brown-chestnut iris, a black-sickle shaped bill, and legs that are nearly black. ''T.l. arenicola'' has a darker chest and underparts and a shorter tail. In its juvenile stages, the thrasher is darker brown, and its feathers looser and fluffy in appearance, especially on the vent.

Range and habitat

This bird ranges from California as far west as the San Joaquin Valley through southern Nevada and southwestern Utah and central and southern Arizona, and is a resident species throughout its range. It resides in some of the harshest climates in its region, including the Sonoran Desert and the San Joaquin Valley, and where annual rainfall only averages 4 to 20 cm. The typical desert habitat consists of dunes, alluvial fans, and flat to gently rolling hills with shallow washes with sparse vegetation. The vegetation that it may utilize includes low vegetation such as saltbush, creosote, cholla cacti, and Mojave yucca. The range of altitude spans as low as 80 m below sea level (in Death Valley) to as high as 1,600 m, although 500 m above sea level is the average. It does not generally coexist with other thrashers due to its habitat, but does overlap breeding ranges and general habitat with the California thrasher in the higher desert regions of its range.

The thrasher has had its population decline in certain regions of its range, notably the Coachella, Imperial and the San Joaquin Valley regions. Major reasons for its decline include urbanization, cultivation of land for livestock