Kevin Clark

San Diego Natural History Museum · Bioservices

Phrynosoma mcallii is restricted to low elevation desert habitats in southeastern California and southwestern Arizona, USA, and adjacent northern Mexico, and is a California Species of Special Concern as a result of habitat loss and fragmentation, and degradation of remaining habitats. Here, we report two mortalities of P. mcallii by vehicles on no...

We studied the foraging behavior of the federally threatened coastal California Gnatcatcher (Polioptila californica), an obligate insectivore, during the non-breeding season, a period of reduced survivorship for this non-migratory passerine due to seasonal aridity and the onset of cold winter storms. During the seasonal dry period in fall (October–...

Shaw's Agave (Agave shawii subsp. shawii) is a rare plant found in only a handful of occurrences within the extreme southwestern corner of the USA in a highly urbanized region. Seedling recruitment of Shaw's Agave in California is visibly low, and viable seed production appears to have been very low in recent years, and has been identified as a pri...

The San Bernardino flying squirrel (Glaucomys oregonensis californicus) is a California Species of Special Concern restricted to montane forests of southern California. We confirmed the distribution of this species in residential areas of the San Bernardino and San Jacinto Mountains with the assistance of citizen scientist volunteers. Project parti...

Endangered Sonoran (Antilocapra americana sonoriensis) and Peninsular (A. a. peninsularis) pronghorn persist largely because of captive breeding and reintroduction efforts. Recovery team managers want to re‐establish pronghorn in their native range, but there is currently uncertainty regarding the subspecies status of extinct pronghorn populations...

Wilmot W. Brown (1870?–1953) collected birds, mammals, amphibians, and reptiles from 1890 until his death in 1953, amassing a collection that forms the core of knowledge of the distribution and taxonomy of the terrestrial vertebrate fauna of Central and South America. His collection of more than 18,000 bird specimens is spread over 25 institutions,...

In 1884 the botanist Cyrus Guernsey Pringle undertook two expeditions from Tucson, Arizona south through the Altar valley and through northwestern Sonora to the coast at the Gulf of California. The first expedition lasted from 17 March-11 April when he was accompanied by his botanical assistant. The second expedition left Tucson on 7 August, return...

We investigated the causes of toe and foot loss and other deformities long observed in urban Brewer’s Blackbirds (Euphagus cyanocephalus) in southern California. Histopathologic evaluation showed that afflicted individuals suffered from infestations of mites compatible with Knemidokoptes spp. (scaly-leg mites). We developed a case definition based...

The El Toro Conservation Area (Conservation Area), approximately 1,000 acres in size, consists of 900 acres that are currently owned and managed by the Federal Bureau of Investigation (FBI) and an additional 100 acres that are owned by the Department of Defense. The Conservation Area was formerly a component of the nearly 5,000-acre El Toro Marine...

We documented bird distribution with respect to elevation and habitat, and to ascertain whether the Sierra Cacachilas supports outlying populations of the endemics of the Sierra de la Laguna.

The objectives of this analysis are to provide a species distributional model (SDM) for the Flat-tailed Horned Lizard (Phrynosoma mcallii) and evaluate its potential for presence based upon habitat and climate characteristics throughout its range. The range of P. mcallii spans southeastern California, southwestern Arizona, northern Baja California,...

No bird has generated so much interest and controversy as has the masked bobwhite (Colinus virginianus ridgwayi). From its discovery in 1884 to the present, this gallinaceous game bird has captured the attention of hunter-naturalists, ornithologists, collectors, game breeders, conservationists and bureaucrats. Believed threatened with extinction th...

In southern California, riparian habitats are a rare but highly valuable resource, providing critical support to a diverse fauna. Drastic reduction and degradation of riparian habitat has led to the decline of many riparian species (e.g., Brinson et al. 1981, USFWS 2005). The Coachella Valley Multiple Species Habitat Conservation Plan (CVMSHCP 2007...

This report presents the results of surveys and nest monitoring conducted for the endangered Least Bell’s Vireo (Vireo bellii pusillus) and Southwestern Willow Flycatcher (Empidonax traillii extimus) at Marine Corps Air Station, Miramar, in the City of San Diego, San Diego County, California. The surveys were conducted on all suitable habitat throu...

We observed a Yellow-billed Cuckoo (Coccyzus americanus) remaining in southern San Diego County from 20 to 28 July 2012. The bird made extensive use of upland habitats as well as the adjacent riparian area. Away from the two known breeding populations, the 82 Yellow-billed Cuckoo observations in southern California since 2000 peak from 15 June to 3...

The largest population of the endangered Southwestern Willow Flycatcher (Empidonax traillii extimus) in California occurs along the upper San Luis Rey River, last surveyed in 2009 by Howell and Kus (2010), who estimated it to contain at least 45 individuals, with 23 males and at least 22 females. They reported this to be an apparent decline of 19%...

After a decline in the U.S. population of Sonoran Pronghorn to less than ~ 30 individuals in 2003 the Sonoran Pronghorn Recovery Team determined that recovery efforts should attempt to reintroduce additional populations within historic habitat. With a program to restore Antilocapra americana sonoriensis to the Kofa National Wildlife Refuge in Arizo...

Santa Cruz Island (SCI) is the largest, most topographically diverse, most speciose, least disturbed, and most intensively researched of the eight California Channel Islands. However, this natural laboratory has itself changed significantly in the recent past, and determining where limited research and management funds should be allocated is a sign...

We evaluated the collecting locales of 251 masked bobwhite (Colinus virginianus ridgwayi) specimens in museum collections. Eighteen were from 4 sites in Arizona—all collected by Herbert Brown. The vast majority (93%) of specimens were from the Mexican State of Sonora. We visited and photographed each of the Arizona collection locations and most of...

This report presents the results of the flat-tailed horned lizard (Phrynosoma mcallii) surveys conducted August 11-13, 2011 on the Borrego ‘B’ and Navarro properties (APNs 141-210-17 & -19; Figure 1). The Borrego ‘B’ property consists of approximately 43 acres (17.4 hectares), while the Navarro property just to the south consists of approximately 1...

This report presents the results of the flat-tailed horned lizard (Phrynosoma mcallii) survey conducted July 6-9, 2011 on the Bighorn property (APNs 141-060-07 & 08; Figure 1). The project area consists of approximately 611 acres (247 ha) of desert habitats bounded by Borrego Valley Road to the west, agricultural areas to the north and south, and d...

The continued fragmentation of natural environments across the continent has raised concern about the ability of sensitive species and ecological communities to persist into the future. To explore the patterns and processes of fragmentation in an arid setting, the vertebrate species present on habitat fragments of various sizes were analyzed in the...

Observé un acontecimiento de depredación de dos volantones del nido de vireo de bell (Vireo bellii pusillus) por la serpiente real de California (Lampropeltis getula californiae) cerca del río San Luis Rey en la parte norte del condado de San Diego, California. Descubrí la serpiente comiendo el primer volantón cuando los adultos estuvieron atacando...

This report summarizes the results of the flat-tailed horned lizard (Phrynosoma mcallii) surveys conducted from July 1-3, 2009 on properties immediately north of Borrego Springs Airport, San Diego County, California. The project area consists of approximately 350 acres of desert habitats bounded by Borrego Springs Airport and Palm Canyon Drive to t...

Nearly two feet long with striking black, white, and red plumage, the Ivory-billed and Imperial Woodpeckers were two of the most impressive woodpeckers in the world. Both species were known to be in serious decline by the end of the nineteenth century and are likely extinct today, though occasional reports of sightings persist. While the Ivory-bill...

Recent pronghorn (Antilocapra americana) translocations to southern California and the establishment of captive populations of endangered desert pronghorn have revived interest in the historical occurrence of pronghorn in the Californias. Adding to this interest is the recent widespread replacement of coastal sage scrub vegetation in southern Calif...

Coastal dune systems were once extensive in southern California. Pervasive human modification of easily disturbed and highly desirable coastal strand areas have left only small remnants. In order to assess the remaining extent of coastal dunes in the region, I have repeatedly surveyed the remaining coastal dune vegetation from Santa Monica, Los Ang...

Just south of the U.S.-Mexico border and east of the rapidly growing city of Tijuana lies a mesa supporting vernal pools, wildflower fields, and rare plant communities. Jesus Maria Mesa is an elevated mesa on the western slopes of Cerro San Isidro, just south of Otay Mountain. Conservation biologists based in San Diego as well as colleagues from Me...

Colonet Mesa is a little known peninsula halfway between Ensenada and San Quintin that supports some of the most robust populations of endangered species and habitats within the California Floristic Province. Hundreds of vernal pools are scattered within a matrix of Martirian sage scrub, maritime chaparral, and coastal dune vegetation communities....

The distribution of the Cactus Wren (Campylorhynchus brunneicapillus) in northwestern Baja California is something of an enigma. Although widely distributed over most of the peninsula, the species is absent from many areas of seemingly suitable habitat in cactus-filled maritime succulent scrub. Immediately north of the border along the coast, Cactu...

The El Toro Conservation Area is one of the most important components of the Orange County Reserve System established under the Orange County Central/Coastal Natural Community Conservation Plan/Habitat Conservation Plan (NCCP/HCP). It contains a significant population of the federally threatened California gnatcatcher, is home to a population of th...

CRYPTANTHA LEIOCARPA (Fischer & C. Meyer) E. GREENE (BORAGINACEAE).—Orange Co., along the coast at Newport Beach on back dunes southeast of Balboa Pier. Thousands of plants in the area from the parking lot at the pier southeast and down the coast nearly to the west jetty at the entrance to Newport Bay. Found with Ambrosia chamissonis, Cakile mariti...

Recent pronghorn (Antilocapra americana) translocations to southern California and the establishment of captive populations of endangered desert pronghorn have revived interest in the historical occurrence of pronghorn in the Californias. Adding to this interest is the recent widespread replacement of coastal sage scrub vegetation in southern Calif...