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Campylorhynchus brunneicapilluscactus wren

By Lara Peterson

Geographic Range

The Cactus Wren is a permanent resident of arid and semi-arid desert regions of the southwestern United States, ranging from southern California, Nevada, and Utah, and central New Mexico and Texas, southward to central Mexico (Anderson 1973; Ricklefs 1968; McCarthy 2000).

Habitat

The Cactus Wren is common throughout the southwestern United States. This arid desert, dominated by cholla and other succulent cacti and spiny trees and shrubs, is characterized by high temperatures, low humidity, and scarce water. Arid hillsides and valleys will also be used. The Cactus Wren is generally found below 4,000 feet, although it is found at elevations up to 6,000 feet in areas of New Mexico. They are common even in urban areas planted with native desert vegetation (Anderson 1973; Ricklefs 1968; McCarthey 2000).

Physical Description

Campylorhynchus brunneicapillus, the largest wren in the United States, is 7-9 inches (17.8-22.9 cm) long. Sexes are similar, characterized by a long, slightly decurved bill, dark crown with a distinctive white stripe over the eye, white throat, gray-brown back streaked with white and black, and white to buff belly and sides, densely spotted at the breast. The wings and tail feathers are mostly black with white barring and the legs are dark. Juveniles resemble adults, but have fewer, lighter chest spots and a shorter tail (Anderson 1973; Udvardy 1994; McCarthey 2000; Gough 1998).

Reproduction

The breeding habitat of the Cactus Wren is successional scrub. Nesting occurs on well defined and defended territories, which are occupied most of the year. The females select a nest site high in native thorny trees and shrubs, showing a preference for cholla cacti. Nest building has also been observed in non-native trees and shrubs as well as in non-thorny native plants, though it is not known if these are only used for roosting purposes. Both the male and female help build the large spherical nest of dry grasses, often lined with feathers. Nests are protected from predators by having only a narrow side entrance and the substrate armature. Breeding begins in late February or early March and continues through June. Clutches consist of 4-5 buff colored eggs, speckled with brown. The female incubates the first clutch for approximately 16 days, beginning with the first egg laid, while the male builds secondary nests and defends the territory. Both parents feed the young and fledging occurs at 19-23 days. After fledging, young continue to stay in the parent's territory for about a month, sleeping in roosting nests; this post-fledgling care is long compared to most temperate-zone passerines. Additional nests, built by the males, can be used to rear second, sometimes third, broods. Clutch size, clutch survival, and additional reproductive behavior are often limited by food availability; fluctuating brood size appears to be an advantageous adaptation to unpredictable desert environments and food availability (Anderson 1973; Ricklefs 1975; Ricklefs 1968; Gough 1998; MacCarthey 2000; Simons and Martin 1990; Farley and Stuart 1994).

  • Average eggs per season
    4
    AnAge
  • Average time to hatching
    16 days
    AnAge

Lifespan/Longevity

Behavior

The Cactus Wren is an active and inquisitive bird, behaviorally well adapted to arid desert climates. Heat stress, due to limited water and the high evaporation characteristic of their environment, is prevented by daily and seasonal shifts in foraging behavior according to temperature; they will move to cooler, shady microclimates and decrease activity during the hottest part of the day. Flight is primarily low over the ground.

The use of thorny trees and shrubs for nesting sites helps defend against predators. However, some predators, especially whipsnakes (Masticophis spp.), do prey on eggs and nestlings. Territories are aggressively defended by the male throughout the breeding season. Nests-destroying behavior was observed by Simons and Simons (1990) when they would place foreign nests inside the territory of a wren, even on non-nesting substrate. This probably represents competition for food and predator-free space. The male Cactus Wren, like other wrens, will often build six or more secondary nests within its territory that can be abandoned at any stage. The female will choose the "cosiest" nest for additional broods, while others are often used purely for roosting purposes.

The territorial song of the Cactus Wren consists of a succession of rapid, harsh, mechanical, unmusical, monotone, low-pitched notes, written as "chur chur chur." Danger and warning calls consist of a rapid buzz of varying intensity. Juveniles often use an indefinite, quiet warble that is less loud and precise than the adult territorial song (Anderson 1973; Parker 1986; Ricklefs 1973; Armstrong 1955; Ricklefs 1968; Simons and Simons 1990; Robbins 1966; Udvaldy 1994).

Communication and Perception

Food Habits

The Cactus Wren primarily eats insects, including ants, beetles, grasshoppers, and wasps. Occasionally, it will take seeds and fruits. Foraging begins late in the morning and is versatile; the cactus wren will search under leaves and ground litter and overturn objects in search of insects, as well as feeding in the foliage and branches of larger vegetation. Increasing temperatures cause a shift in foraging behavior to shady and cooler microclimates, and activity slows during hot afternoon temperatures. Almost all water is obtained from food, and free standing water is rarely used even when found (Udvardy 1994; Ricklefs 1968; McCarthey 2000).

Economic Importance for Humans: Positive

The Cactus Wren disperses potentially important semi-arid rangeland plants through the material used in building nests; viable seeds can be spread over long distances in this manner (Milton et al. 1998).

Economic Importance for Humans: Negative

No information is available on negative impacts.

Conservation Status

The Cactus Wren is common throughout its range and is not considered threatened or endangered though it is protected, along with all songbirds, by the Migratory Bird Treaty Act. Their native habitat is not considered threatened and the Cactus Wren also does well in urban areas planted with native species. There are no immediate management needs (McCarthey 2000).

Other Comments

The cactus wren has been the state bird of Arizona since 1931; its presence and song are considered characteristic of southwestern deserts.

The genus Campylorhynchus is derived from Greek words meaning curved beak. The specific epithet is Latin; brunneus means brown, and capillus means hair, denoting the brown cap and back (Anderson 1973; McCarthey 2000).

Contributors

Lara Peterson (author), University of Michigan-Ann Arbor, Terry Root (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

visual

uses sight to communicate

References

Anderson, A. 1973. The Cactus Wren. Tucson, AZ: University of Arizona Press.

Anderson, E. 1955. The Wren. London: Collins.

Farley, G., J. Stuart. 1994. Atypical nesting sites of the Cactus Wren. Texas Journal of Science, 46: 193-195.

Gough, G. 1997. "Cactus Wren, (Patuxent Wildlife Research Center, Laurel, MD)" (On-line). Accessed 10/22/00 at http://www.mbr-pwrc.usgs.gov/id/framlst/i7130id.html.

McCarthey, T. "Cactus Wren (Campylorhynchus brunneicapillus)" (On-line). Accessed 10/22/00 at http://www.gf.state.az.us/frames/fishwild/idx_ngam.htm.

Milton, S., W. Dean, G. Kerley, H. Hoffman, W. Whitford. 1998. Dispersal of seeds as nest material by the cactus wren. Southwestern Naturalist, 43: 449-452.

Parker, K. 1986. Partitioning of foraging space and nest sites in a desert shrubland bird community. American Midland Naturalist, 115: 255-267.

Ricklefs, R. 1972. Patterns of growth in birds: growth and development of Cactus wren. Condor, 77: 34-45.

Ricklefs, R., F. Hainswor. 1968. Temperature dependent behavior of Cactus Wren. Ecology, 49: 277-278.

Simons, L., T. Martin. 1990. Food limitation of avian reproduction: an experiment with the Cactus Wren. Ecology, 71: 869-876.

Simons, L., L. Simons. 1990. Experimental studies of nest-destroying behavior by Cactus Wren. Condor, 92: 855-860.

Uvaldy, M., r. Farrand Jr.. 1994. National Audubon Society field guide to North American birds: western region. New York, NY: Knopf: Distributed by Random House.

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