Distribution: NW Mexico (Baja California; Cape St. Lucas, Michoacan [Dixon 1969])
Type locality: Cape St. Lucas, Baja California.
Catalog Number: USNM 5304
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Year Collected: 1860
Locality: Cape San Lucas (= Cabo San Lucas), Baja California Sur, Mexico
Sierra de la Laguna Dry Forests Habitat
This taxon is found in the Sierra de la Laguna dry forests ecoregion, which was once an isolated island, containing a large number of endemic species. After sufficient mountain uplift and the joining the Baja Peninsula mainland, this ecoregion underwent significant speciation, and is thus today high in species diversity; this portion of the peninsula contains the majority of the species found in the southern part of the Baja Peninsula. The region is shaped by a vast complex of granitic mountains, running southward from the Gulf of California to the Pacific. These mountains are dissected by valleys and canyons, and surrounded by vast plateaus.
The forest is transitional both with the pine oak forests at higher elevations, and with the xeric scrub at lower portions. The dry forest of Sierra de la Laguna is characterized by abundance of low trees and scrubs, and poor vertical stratification. The dominant tree species in the subtropical forest are Mauto (Lysiloma divaricatum), Palo Blanco (L. candida), Elephant Tree (Bursera microphylla) and Palo Zorrillo (Hesperalbizia occidentalis). Herbaceous elements are poorly developed, but their representatives are Caribe (Cnidoscolus angustidens), Spiny Aster (Chloracantha spinosa var. strictospinosa), Solanum spp., and cacti such as Biznaga (Ferocactus spp).
A number of reptilian taxa are found in the ecoregion, including: the endemic Baja California Rat Snake (Bogertophis rosaliae); Hunsaker's Spiny Lizard (Sceloporus hunsakeri); Belding's Orange-throated Whiptail (Cnemidophorus hyperythrus); Spiny Chuckwalla (Sauromalus hispidus NT); San Lucan Leaf-tailed Gecko (Phyllodactylus unctus NT); Baja California Night Snake (Hypsiglena slevini), a Mexican endemic rangeing from Bahía San Juanico, in the east-central Baja California Peninsula, southward continuously Cabo San Lucas (as well as on the island of Santa Margarita and on Cerralvo and Danzante islands in the Gulf of California; and Hunsaker's Spiny Lizard (Sceloporus hunsakeri), endemic to the Cape Region of Baja California Sur and the Gulf of California islands of Espiritu Santo, Gallo, Ballena and Partida Sur.
There are a number of mammalian species occurring in the Sierra de la Laguna dry forests. Among the mammals found here are: Eva's Desert Mouse (Peromyscus eva), endemic to Baja California Sur; Mexican Funnel-eared Bat (Natalus stramineus); the near-endemic Peninsular Bat (Myotis peninsularis EN), chiefly found in Baja California Sur; Dalquest's Pocket Mouse (Chaetodipus dalquesti VU), known only from the Cape Region of Baja California Sur.
San Lucan Xeric Scrub Habitat
This taxon is found in the San Lucan xeric scrub, an ecoregion situated at the southern-most part of the Baja Peninsula of Mexico; this diverse landscape of mountains, valleys, and plateaus is covered with a variety of species of xeric vegetation. This neotropical ecoregion is classifed within the Deserts and Xeric Scrublands biome. Plants and animals of this region evolved independently before the Baja Peninsula, a previous island during the Miocene, joined the mainland. An arid climate supports a number fauna and species, about ten percent which of which are endemic.
The ecoregion took shape in the Miocene as an isolated landform prior to joining the peninsula, and thus can be considered an biogeographical island of vegetation. This arid landscape is composed of a vast, rugged complex of granitic mountains, valleys, canyons, and plateaus. The ecoregion occupies the plateaus between the coast and the lower limits of the dry forests, which begin around 250 meters. Precipitation is about 400 millimetres annually.
Some elements of dry forest habitat are present in this ecoregion, but xeric elements are dominant and include Chain-link Cholla (Opuntia cholla); Elephant Tree (Bursera microphylla), at the southern limit of its range here and extending north to the Waterman Mountains in the USA; Mauto (Lysiloma divaricata); Organ Pipe Cactus (Stenocereus thuberi), Mala Mujer (Cnidoscolus angustidens), Yucca spp., and Barrel Cacti (Ferocactus spp). Herbaceous elements in the ecoregion include Plantago linearis, Bouteloua hirsuta, and Commelina coelestis.
The San Lucan xeric scrub harbours 31 of 48 of the reptile species for the Cape Region. Almost a third of the wider regional recorded species of collembola arthropods and spiders (30 of 138 species, respectively) occur in this ecoregion. In general, over ten percent of animal and plant species found here are endemic.
Within the San Lucan xeric scrub ecoregion, reptilian taxa include: the endemic Island Burrowing Sand Snake (Chilomeniscus punctatissimus); the endemic Isla Cerralvo Snake (Chilomeniscus savagei), restricted solely to Cerralvo Island; the Cape Arboreal Spiny Lizard (Sceloporus licki), a near-endemic restricted to the southern portion of the Baja Peninsula; the near-endemic Spiny Chuckwalla (Sauromalus hispidus NT), found only on Angel de la Guarda Island, Granito, Mejía, Pond, San Lorenzo Norte, San Lorenzo Sur, and other islands in Bahía de los Ángeles, including Cabeza de Caballo, La Ventana, Piojo, Flecha, Mitlàn, and Smith, Gulf of California; the near-endemic San Lucan Leaf-toed Gecko (Phyllodactylus unctus NT), found only on southern Baja Peninsula and some islands within the Gulf of California: Gallo, Partida Sur, Espiritu Santo, Ballena, Gallina and Cerralvo. There are only a small number of anuran species present in the ecoregion: Red-spotted Toad (Anaxyrus punctatus); and Pacific Chorus Frog (Pseudacris regilla).
The Espiritu Santo Island Antelope Squirrel (Ammospermophilus insularis) is endemic to the San Lucan xeric scrub ecoregion and is found only on the island of Espiritu Santo in the Gulf of California. Among threatened mammals occurring in the ecoregion are: the near-endemic Dalquest's Pocket Mouse (Chaetodipus dalquesti VU), known from the Cape Region of the Baja California Peninsula.
Threatened mammals in the ecoregion include: the near-endemic Peninsular Myotis (Peninsular Myotis EN), found only on southern Baja Peninsula; Fish-eating Bat (Myotis vivesi VU), a near-endemic occurring chiefly on the near-shore islands off of the southern Baja Peninsula and mainland Sonora; Mexican Long-tongued Bat (Choeronycteris mexicana NT); and the Lesser Long-nosed Bat (Leptonycteris yerbabuenae VU).
Baja California Desert Habitat
This taxon is found in the Baja California Desert ecoregion, located on most of the western side of the Baja Peninsula, containing varied habitats such as mountains, plains and coastal dunes. This desert is one of the largest and best preserved in Mexico, and due to its isolation, contains a high level of species richness and endemism. A series of ophiolytes (formations of gabrum, ultramafic rocks, and volcanic lava) surround the most prominent orographic feature: The San Andres mountain range. Overall, the climate is arid with variable temperature. The isolated nature of the peninsula, and its proximity to the sea, maintains a measure of humidity, and creates a stable diurnal temperature.
The predominant vegetation associations are composed of xeric scrub, which have been subdivided in diverse categories according to dominant species and the ecological conditions in which they occur. Thick-stemmed trees and shrubs, growing on rocky volcanic soils, cover the highest parts of the mountain ranges. Dominant plant species are Ambrosia camphorata, Common Stork's-bill (Erodium cicutarium), and Astragalus prorifer. The Boojumtree (Fouquieria columnaris) can be also found at elevations up to 1200m. Many species of cacti are present. Dominant species within the Baja California Desert vary with elevation. Epiphytes such as Small Ballmoss (Tillandsia recurvata) and Cudbear (Rocella tinctoria) grow in low elevation, humid areas, and account for a majority of the perennial vegetation. Areas previously submerged under the sea (in the Miocene era) are now covered by highly saline and alkaline-tolerant species, such as Ambrosia magdalenae, El Vizcaino Agave (Agave vizcainoensis), Datilillo (Yucca valida), Pitaya Agria (Stenocereus gummosus), and Porter's Muhly (Muhlenbergia porteri). Dune vegetation includes Creosote Bush (Larrea tridentata), Barclay's Saltbush (Atriplex barclayana), Rush Milkweed (Asclepias subulata) and Nicolletia trifida.
There are a number of reptilian taxa found in the Baja California Desert including the endemic Baja California Brush Lizard (Urosaurus lahtelai). The Baja California Legless Lizard (Anniella geronimensis EN) is also endemic to the ecoregion, and is restricted to a narrow strip around 87 kilometres (km) long, ranging from about six km north of Colonia Guerrero, southerly to a point south of Punta Baja at the northern edge of Bahia El Rosario. This legless lizard extends to at most four km inland in the Arroyo Socorro, but otherwise found only in the coastal zone; A. geronimensis also occurs on Isla San Gerónimo. Also found here is the San Lucan Leaf-toed Gecko (Phyllodactylus unctus NT), a species not endemic to the ecoregion, but restricted to the southern Baja Peninsula and the Gulf of California islands of Partida Sur, Gallo, Espiritu Santo, Ballena, Gallina and Cerralvo.
There are only a few amphibians found in the ecoregion. Anuran taxa occurring here include: California Chorus Frog (Pseudacris cadaverina); Pacific Chorus Frog (Pseudacris regilla); and Canyon Treefrog (Hyla arenicolor). Also found here is the Plateau Toad (Anaxyrus compactilis), an endemic to the lower central Mexican Plateau and Baja California Desert; another toad occurring in the ecoregion is the Western Toad (Anaxyrus boreas NT). The Channel Islands Slender Salamander (Batrachoseps pacificus) was earlier thought to occur in this ecoregion, but genetic data shows that this taxon is strictly endemic to the Channel Islands of California.
Endemic mammals include San Quintín Kangaroo Rat (Dipodomys gravipes CR), and Baja California Rock Squirrel (Spermophilus atricapillus EN). Other mammals that are classified as special status are the Lesser Long-nosed Bat (Leptonycteris yerbabuenae VU). Some shallow coastal saltwater lagoons protruding into the Baja California Desert along the Pacific Ocean provide key breeding habitat for the Grey Whale (Eschrichtius robustus CR). One of the largest such breeding waters is the remote San Ignacio Lagoon, extending many kilometres inland and rarely exceeding fifteen metres in depth.
Important sites for avian conservation include the Ojo de Liebre lagoon, along the Pacific coast, which is home to millions of overwintering ducks and geese. Bird species in the Baja California Desert include such notable raptor taxa as Golden Eagle (Aquila chrysaetos), Peregrine Falcon (Falco peregrinus), Southern Crested Caracara (Caracara plancus), Osprey (Pandion haliaeutus), and Burrowing Owl (Athene cunicularia).
Habitat and Ecology
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