Cactus wren

Campylorhynchus brunneicapillus

TAXONOMY

Picocolaptes brunneicapillus Lafresnaye 1835, Guaymas, Mexico. Eight subspecies recognized.

OTHER COMMON NAMES

French: Troglodyte des cactus; German: Kaktuszaunkönig; Spanish: Matraca Desértica.

PHYSICAL CHARACTERISTICS

7.2-7.6 in (18-19 cm); 1.2-1.6 oz, mean 1.4 oz (33.4-46.9 g, mean 38.9 g). The largest species of wren in the United States. The bird is chocolate-brown above, with a plain cap. The back is heavily streaked with black and white, the wings prominently barred with buff and blackish, the tail feathers with alternating blackish brown and gray-brown bars, the outer tail feathers conspicuously barred black and white. Underparts are buff-white and heavily spotted with black, especially on chest. Lower flanks are buff. It has a conspicuous white supercilium. Eyes are reddish brown, bill dull black with paler base, legs pinkish brown. Sexes are similar. The juvenile has less well-defined streaks and spots; eye color is muddy gray-brown.

DISTRIBUTION

Resident from southeast California, southwest Nevada, sourth-ern Arizona and New Mexico, southwest Texas through central Mexico as far south as Michoacán and Hidalgo; Baja California.

HABITAT

Semi-desert from sea level to 4,500 ft (1,400 m), rarely to 6,500 ft (2,000 m), in various vegetation-types, provided that there are spiny cacti such as cholla for nesting. Will adapt to badly degraded habitat so long as some spiny cactus nesting sites remain.

BEHAVIOR

A rambunctious and noisy bird, usually found in pairs or family parties. Song is a loud, harsh series of "jar-jar-jar" notes, frequently delivered from the top of a cactus or other perch. Roosts in nests that are often built for that purpose; old birds may roost alone, fledged broods are usually together.

FEEDING ECOLOGY AND DIET

Majority of food is invertebrate (ants, wasps, spiders, caterpillars, etc.); also eats small frogs and lizards. Vegetable matter includes cactus seeds and fruit; may visit bird feeders. Can exist without drinking, but will drink if water is available. Tends to feed on the ground, overturning litter and stones for prey.

REPRODUCTIVE BIOLOGY

Monogamous. Nest is a conspicuous ovoid ball with a side entrance hole, made of dry grasses and fibers and lined with feathers. Nests are almost invariably located in spiny cacti; little effort is made at concealment. Eggs usually number three to five, sometimes two to seven, are buff or pinkish in color and finely speckled with reddish brown. Populations in Baja California tend to lay smaller clutches. Incubation is by the female alone, about 16 days in length. Young are fed by both sexes for 19-23 days. In Arizona, nesting may begin as early as January, more usually February. Multibrooded; may attempt up to six broods a year, but only three successful broods are reared. Unlike tropical members of its genus, additional birds (other than the breeding pair) rarely help at the nest.

CONSERVATION STATUS

Not threatened. In suitable habitat one of the most abundant species. Can withstand significant habitat modification provided some spiny cactus remain for nesting sites.

SIGNIFICANCE TO HUMANS

A familiar and popular local species, it is the state bird of Arizona. ♦

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