Introduction

Adult Cactus Wren, ssp. C. b. anthonyi, Sonoran Desert, Riverside Co., CA, 4 April.

Cactus Wren pair, ssp. C. b. anthonyi, Mojave Desert, Kern Co., CA, 9 November.

Adult Cactus Wren, ssp. C. b. anthonyi, Sonoran Desert, Maricopa Co., AZ, May.

Adult Cactus Wren, ssp. C. b. couesi, Chihuahuan Desert, Starr Co., TX, 15 November.

Figure 1. Distribution of the Cactus Wren.

Figure 4. Cactus Wren range in s. California, 2010.

“Perched atop a thorny bush, he breaks the sweltering stillness of a summer afternoon with his harsh scolding notes. The noisy aggressive Cactus Wren can be heard throughout the day, even when most other desert dwellers seek seclusion in some shady niche”

(Tveten 1993: 280).

A non-migratory resident of scrub communities of the southwestern United States and northern and central Mexico, the enigmatic Cactus Wren maintains a conspicuous and ubiquitous presence across wide swaths of desert even as it declines to the point of crisis in the fragmented and fire-prone cactus scrub communities of coastal southern California and northwestern Baja California. A true xerophile that can meet its water needs through food intake alone, its diet of insects, occasional small reptiles or amphibians, fruit pulp, seeds, and juice from wounds in cactus usually provides enough liquid to sustain individuals in their arid surroundings.

Large size and conspicuous, noisy behavior distinguish Cactus Wrens from all other wrens with which they might occur. The nest is a large, globular chamber with a tunnel-shaped passageway and “doorstep” or perch near the entrance. Building the year-round, males often establish several secondary nests—used for roosts by adults and fledglings and as breeding nests for subsequent broods—while their mates incubate eggs. This species may fledge as many as 3 broods a year.

In addition to the repetitive, single, staccato note frequently given by the male, the Cactus Wren’s repertoire contains at least 32 variations of the typical Adult Song. These variations are marked by distinct syllable patterns of characteristic length and rate. The female’s song, rarely heard, is weaker and higher pitched than that of the male.

Although the Cactus Wren is considered a hardy species that readily adapts to various human activities and landscape modifications in the desert, populations that occupy coastal sage scrub in southern California are declining in the wake of several large wildfires, and in response to other stressors not completely understood, but presumably linked to fragmentation of habitat and urbanization in general.

For this revision, nearly all of the primary literature cited in the original account has been reviewed, and in some cases the updated account provides revised interpretations of the information therein. The bibliography for the initial account by Glenn A. Proudfoot, Dawn A. Sherry, and Steve L. Johnson (2000) contained more than 100 entries, and the account’s introduction made special mention of works by A. H. Anderson, A. Anderson, R. E. Ricklefs, and F. R. Hainsworth. In a 6-part journal series that culminated in a book, The Cactus Wren, boundless life-history information is provided from 30 years of study in southwestern Arizona (Anderson and Anderson 1957, 1959, 1960, 1961, 1962, 1963, 1973). Also conducting research in southern Arizona, but focusing more on nesting (for example, nestling conditioning and development of homeothermy), Ricklefs (1966, 1967, 1968) and Ricklefs and Hainsworth (1966, 1968a, 1968b, 1969) provided key physiological information on the species. Other important papers addressing ecology of Cactus Wren in arid environments of Arizona and New Mexico include: Marr 1981, Marr and Raitt 1983, Simons and Martin 1990, and Simons and Simons 1990 and 1993.

During the past decade, shrinking populations in coastal s. California and nw. Baja California have received increased attention; this revision bolsters the original account’s treatment of these populations.