San Diego Management & Monitoring Program


Coastal cactus wren
Campylorhynchus brunneicapillus sandiegensis

Vertebrata

Vertebrata
Kingdom Phylum Subphylum Class Order Suborder Family

Current distribution rangewide

Resident species from S. Calif. south to S. Baja Calif., S. Nevada, SW Utah, W. and south central Arizona, S. New Mexico, and central Texas south to Mexico [1].


Known Populations in San Diego County

In San Diego County, the coastal cactus wren is known to occur at Lake Hodges/San Pasqual Valley, Lake Jennings, South Sweetwater Reservoir/San Miguel Ranch, and Salt Creek/Otay Mesa, Camp Pendleton/ Fallbrook NWS; San Pasqual Valley and Lake Hodges; San Diego and El Cajon; and Otay River [3, 4].


List status

CSC


Habitat affinities

Closely associated with three species of cacti and occurs almost exclusively in thickets of cholla (Opuntia prolifera) and prickly pear (Opuntia littoralis and Opuntia oricola) dominated stands of coastal sage scrub below 457 meters in elevation on mesas and lower slopes of the coast ranges [2].


Taxonomy and genetics

Eight subspecies are recognized with the subspecies falling into roughly two groups the affinis group (peninsular forms) and brunneicapillus group (continental forms) [2]. Recent USGS genetic studies showed genetic differentiation between four distinct genetic clusters: Orange County and MCB Camp Pendleton/ Fallbrook NWS; San Pasqual Valley and Lake Hodges; San Diego and El Cajon; and Otay River [3, 4].


Seasonal activity

Exhibits year-long, diurnal activity. The species is not migratory [5].


Life history/ reproduction

Breeds from March into June; clutch size is 4-5 eggs, with a range of 3-7 eggs [6]. Two broods per season are common; incubation is 15-18 days, by the female only [7]. The altricial nestlings fledge at 17-23 days, with an average of 21 [8]. The young may return to roost in the nest after fledging. The young become independent at about 1 mo after leaving the nest; sometimes the young help feed the young of later broods [6]. Overall adult survival rate reported as 50.6% during a six year study [7].


Diet and foraging

Forages on the ground and in low vegetation for insects and other small invertebrates, cactus fruits and other fruits, seeds and nectar [7, 9]. Fruits make up 15-20 percent of the annual diet [10].


Dispersal

Generally considered to have low dispersal; in Arizona, of 55 nestlings banded, 41 dispersed from the natal site by 45 days postfledging; males remain near the natal site, usually dispersing only as far as parental territorial behavior dictated [2].


Threats

The most important threat to coastal cactus wren has been the loss and fragmentation of cactus scrub habitat as a result of urban and agricultural development [2]. A second primary threat is large wildfires that cause direct mortality of birds and destroy cactus scrub, which can take many years to recover [11, 12, 13, 14].Other threats include invasive plant species reducing open habitat for foraging, [15, 16] declines in productivity during drought, and predation by domestic cats, roadrunners, snakes, loggerhead shrikes, and especially Cooper's hawks.


Coastal cactus wren sources