This report is the result of a cooperative effort by the Rocky Mountain Research Station and the USDA Forest Service Region 3, with participation by the Arizona Game and Fish Department and the Bureau of Land Management. It assesses the state of knowledge related to the conservation status of the cactus ferruginous pygmy-owl in Arizona. The population decline of this owl has been attributed to the loss of riparian areas before and after the turn of the 20th century. Currently, the cactus ferruginous pygmy-owl is chiefly found in southern Arizona in xeroriparian vegetation and wellstructured upland desertscrub. The primary threat to the remaining pygmy-owl population appears to be continued habitat loss due to residential development. Important information gaps exist and prevent a full understanding of the current population status of the owl and its conservation needs.
"With detailed information about identification, calls, habitat, breeding, nesting, and behavior, this reference guide has the most up-to-date information about natural history, taxonomy, biology, ecology, migration and conservation status."--Book jacket.
In prehistoric times, the Santa Cruz River in what is now southern Arizona saw many ebbs, flows, and floods. It flowed on the surface, meandered across the floodplain, and occasionally carved deep channels or arroyos into valley fill. Groundwater was never far from the surface, in places outcropping to feed marshlands or ciénegas. In these wet places, arroyos would heal quickly as the river channel revegetated, the thriving vegetation trapped sediment, and the channel refilled. As readers of Requiem for the Santa Cruz learn, these aridland geomorphic processes also took place in the valley as Tucson grew from mud-walled village to modern metropolis, with one exception: historical water development and channel changes proceeded hand in glove, each taking turns reacting to the other, eventually lowering the water table and killing a unique habitat that can no longer recover or be restored. Authored by an esteemed group of scientists, Requiem for the Santa Cruz thoroughly documents this river—the premier example of historic arroyo cutting during the late nineteenth and early twentieth centuries, when large floodflows cut down through unconsolidated valley fill to form deep channels in the major valleys of the American Southwest. Each chapter provides a unique opportunity to chronicle the arroyo legacy, evaluate its causes, and consider its aftermath. Using more than a collective century of observations and collections, the authors reconstruct the circumstances of the river’s entrenchment and the groundwater mining that ultimately killed the marshlands, a veritable mesquite forest, and a birdwatcher's paradise. Today, communities everywhere face this conundrum: do we manage ephemeral rivers through urban areas for flood control, or do we attempt to restore them to some previous state of perennial naturalness? Requiem for the Santa Cruz carefully explores the legacies of channel change, groundwater depletion, flood control, and nascent attempts at river restoration to give a long-term perspective on management of rivers in arid lands. Tied together by authors who have committed their life’s work to the study of aridland rivers, this book offers a touching and scientifically grounded requiem for the Santa Cruz and every southwestern river.
Fifty years ago, riparian habitats were not recognized for their extensive and critical contributions to wildlife and the ecosystem function of watersheds. This changed as riparian values were identified and documented, and the science of riparian ecology developed steadily. Papers in this volume range from the more mesic northwestern United States to the arid Southwest and Mexico. More than two dozen authors-most with decades of experience-review the origins of riparian science in the western United States, document what is currently known about riparian ecosystems, and project future needs. Topics are widespread and include: interactions with fire, climate change, and declining water; impacts from exotic species; unintended consequences of biological control; the role of small mammals; watershed response to beavers; watershed and riparian changes; changes below large dams; water birds of the Colorado River Delta; and terrestrial vertebrates of mesquite bosques.
