BREEDING BIRD COMMUNITIES AND NEST PLANT SELECTION IN CHIHUAHUAN DESERT HABITATS IN SOUTH-CENTRAL NEW MEXICO

we examined the significance of arroyo-riparian habitat to birds in the Chi- huahuan Desert of south-central New Mexico. Nests (N = 620) of 27 species were monitored during 1993-1995. Twenty-three species nested in arroyos and 20 species nested in uplands. Northern Mockingbirds (Mimus polyglottos), Rock Wrens (Salpinctes obsoletus), and Ver- dins (Auriparus jlmiceps) nested most frequently in arroyos. Black-throated Sparrows (Am- phispiza bilineata), Northern Mockingbirds, and Scott's Orioles (Zcterus parisorum) nested most frequently in uplands. Nest density in arroyos was more than twice that of uplands (0.64 nests/ha versus 0.27 nests/ha). Nest success and predation rates did not differ between arroyos and uplands for Black-throated Sparrows, Northern Mockingbirds, and Crissal Thrashers (Tomstoma crissale). Nest predation was the primary cause of mortality to eggs and nestlings in both habitats. Torrey yucca (Yucca torreyi), javelina bush (Condo& war- no&i), and little-leaf sumac (R&s microphylla) were the most frequently used nest sub- strates, even though these shrubs were among the lowest in density. Maintaining this habitat and protecting sparse shrub species used as nest substrates may have long term importance