''Gambelia sila'', commonly known as the blunt-nosed leopard lizard, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of lizard in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Crotaphytidae The Crotaphytidae, or collared lizards, are a family (biology), family of desert-dwelling reptiles native to the Southwestern United States and northern Mexico. Alternatively they are recognized as a subfamily, Crotaphytinae, within the clade Ple ...

. The species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to southern

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

Taxonomy

''Gambelia sila'' was originally described by

Leonhard Stejneger Leonhard Hess Stejneger (30 October 1851 – 28 February 1943) was a Norwegian-born American ornithologist, herpetologist and zoologist. Stejneger specialized in vertebrate natural history studies. He gained his greatest reputation with repti ...

in 1890 as ''Crotaphytus silus''. The type locality is

Fresno Fresno (; ) is a city in the San Joaquin Valley of California, United States. It is the county seat of Fresno County, California, Fresno County and the largest city in the greater Central Valley (California), Central Valley region. It covers a ...

, California. In 1900

Cope A cope ( ("rain coat") or ("cape")) is a liturgical long mantle or cloak, open at the front and fastened at the breast with a band or clasp. It may be of any liturgical colour. A cope may be worn by any rank of the Catholic or Anglican clerg ...

believed the lizard to be a

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

of the long-nosed leopard lizard, ''C. wislizenii'', and classified it as ''C. w. silus''. Based on differences in bony plates on the head, the presence or absence of gular folds, and head shape, ''Crotaphytus silus'' was reclassified into the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Gambelia'' by H.M. Smith in 1946, retaining the

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

"''silus'' ". ''Gambelia'' is the generic name for leopard lizards in the family

. ''Gambelia sila'' is similar to the lizards in the genus ''Crotaphytus'', the difference is that the latter have fracture planes in their tails. This allows the tails to break off when grasped by predators. This reclassification remained controversial until Montanucci in 1970 proposed the argument for specific classification based on the differences between the long-nosed and blunt-nosed leopard lizards. Eventually the

scientific name In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

was changed from "''Gambelia silus'' " to "''Gambelia sila'' " to agree in

gender Gender is the range of social, psychological, cultural, and behavioral aspects of being a man (or boy), woman (or girl), or third gender. Although gender often corresponds to sex, a transgender person may identify with a gender other tha ...

Geographic range

''Gambelia sila'' is found only in Southern California. It used to be found in the

San Joaquin Valley The San Joaquin Valley ( ; Spanish language in California, Spanish: ''Valle de San Joaquín'') is the southern half of California's Central Valley (California), Central Valley. Famed as a major breadbasket, the San Joaquin Valley is an importa ...

and adjacent foothills ranging from

Stanislaus County Stanislaus County ( ; ) is a county located in the San Joaquin Valley of the U.S. state of California. As of 2023, its estimated population is 564,404. The county seat is Modesto. Stanislaus County makes up the Modesto metropolitan statistic ...

, in the south, to the northern tip of

Santa Barbara County Santa Barbara County, officially the County of Santa Barbara (), is a county located in Southern California. As of the 2020 United States census, the population was 448,229. The county seat is Santa Barbara, and the largest city is Santa M ...

. However, it is only found in elevations of 800 meters (2,600 feet) and below. ''Gambelia sila'' can now only be found in isolated sections of undeveloped land in the San Joaquin Valley. In the northern part of the San Joaquin Valley it can be found in the Ciervo Hills, Tumey Hills, Panoche Hills, Anticline Ridge, Pleasant Valley, and the Lone Tree, Sandy Mush Road, Whites Bridge, Horse Pasture, and Kettleman Hills Essential Habitat Areas. In the southern part of the San Joaquin Valley it can be found in Pixley National Wildlife Refuge, Liberty Farm, Allensworth, Kern National Wildlife Refuge, Antelope Plain, Buttonwillow, Elk Hills, Lost Hills, and Tupman Essential Habitat Areas; on the Carrizo and Elkhorn Plains; north of

Bakersfield Bakersfield is a city in and the county seat of Kern County, California, United States. The city covers about near the southern end of the San Joaquin Valley, which is located in the Central Valley region. Bakersfield's population as of the ...

around Poso Creek; in western

Kern County Kern County is a county (United States), county located in the U.S. state of California. As of the 2020 United States census, 2020 census, the population was 909,235. Its county seat is Bakersfield, California, Bakersfield. Kern County compris ...

in the area around the towns of Maricopa, McKittrick, and Taft; at the Kern Front Oil Field; at the base of the

Tehachapi Mountains The Tehachapi Mountains (; Kawaiisu: ''Tihachipia'', meaning "hard climb") are a mountain range in the Transverse Ranges system of California in the Western United States. The range extends for approximately in southern Kern County and northwe ...

on the

Tejon Ranch Tejon Ranch Company (), based in Lebec, California, is one of the largest private landowners in California. The company was incorporated in 1936 to organize the ownership of a large tract of land that was consolidated from four Mexican land gr ...

; and just west of the

California Aqueduct The Governor Edmund G. Brown California Aqueduct is a system of canals, tunnels, and pipelines that conveys water collected from the Sierra Nevada and valleys of Northern and Central California to Southern California. Named after California Gov ...

on the Tejon Ranch and

Rancho San Emidio Rancho San Emidio was a Mexican land grant in present-day Kern County, California given in 1842 by Governor Juan Alvarado to José Antonio Dominguez. The grant was located along San Emigdio Creek in the northeastern foothills of the San Emigdi ...

Diet

The diet of ''Gambelia sila'' mainly consists of an assortment of

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

s and other lizards. The

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s that it normally preys on are:

grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are amongst what are possibly the most ancient living groups of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grassh ...

beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...

bee Bees are winged insects closely related to wasps and ants, known for their roles in pollination and, in the case of the best-known bee species, the western honey bee, for producing honey. Bees are a monophyletic lineage within the superfamil ...

wasp A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder ...

s, and

ant Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...

s. The blunt-nosed leopard lizard is also known to eat other species of lizards, and sometimes eats its own offspring. It is an agile predator, with the ability to leap 60 centimetres (2 feet), making it very easy for it to catch its prey.

Physical characteristics

The blunt-nosed leopard lizard (''Gambelia sila'') is a relatively large lizard in the

. It has a long, regenerative tail; long, powerful hind limbs; and a short, blunt snout. Adult males are slightly larger than females, ranging in size from in length, excluding tail. Females are . Males weigh , females . Although the blunt-nosed leopard lizard is darker than other leopard lizards, it exhibits tremendous variation in

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

color and pattern. The background color ranges from yellowish or light gray-brown to dark brown, depending on the surrounding soil color and vegetation. The underside is uniformly white. It has rows of dark spots across the back, alternating with white, cream-colored or yellow bands. ''Gambelia sila'' is relatively unique among crotaphytids in that sexes cannot be distinguished by permanent coloration and patterning, but both males and females develop breeding coloration, and these colors and patterns differ markedly between them. Also, unlike almost all other crotaphytids, juvenile ''G. sila'' obtain a yellow coloring under the hind limbs and tails. The signs of yellow coloration in young ''G. sila'' might indicate that some type of signal is being sent to adult leopard lizards, although no testing has been done. Possibly the purpose of yellow coloration is to signal to adults that carriers are too small to breed, and, therefore, do not pose a competitive threat. Conversely, the bright yellow coloration of juveniles could serve as a means of avoiding predators.

Breeding

In ''G. sila'' the breeding season is initiated in April and lasts into or through June. Male and female pairs are commonly seen together and often occupying the same burrow systems. In June and July, 2-6

eggs An egg is an organic vessel in which an embryo begins to develop. Egg, EGG or eggs may also refer to: Biology * Egg cell, the female reproductive cell (gamete) in oogamous organisms Food * Eggs as food Places * Egg, Austria * Egg, Switzerland ...

averaging are laid. Environmental conditions may influence the number of

clutches A clutch is a mechanical device that allows an output shaft to be disconnected from a rotating input shaft. The clutch's input shaft is typically attached to a motor, while the clutch's output shaft is connected to the mechanism that does the ...

females produce each year, but they usually lay only one clutch. After about a two-month incubation period, the young hatch. They range in size at birth from , excluding tail. Some young blunt-nosed leopard lizards may grow to double their hatching size prior to their first winter. During the breeding season, females are recognized by the bright red-orange markings on the sides of the head and body and the undersides of the thighs and tail. Males may also develop a color of salmon to bright rusty-red over the entire undersides of the body and limbs. This new coloring may continue indefinitely in males. Male and female blunt-nosed leopard lizards exhibit several different physical behaviors. The simple headbob is a single, vertical motion of only the head whereas the pushup involves an up and down movement of the forelimbs and a headbob. Rocking and fighting displays are restricted to males. Rocking involves rotating the head and shoulders in a forward, circular motion. When one male encounters another, it exhibits a threat-challenge display. It consists of inflating the body, extending the hind limbs, arching the back, and performing pushups in rapid succession. Two fighting males will align side by side while facing in opposite directions. Each will then attempt to bite the other as they lash their tails and jump toward each other. Females exhibit a rejection posture when a male attempts copulation. With back arched, body inflated, limbs extended, and mouth open, she always faces the male or moves to orient herself laterally to the male.

Conservation status

''Gambelia sila'', also known as the blunt-nosed leopard lizard, is listed as a federal endangered species and is listed by the State of California as an endangered species and fully protected species. This species is thought to have declined as a result of

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

and

habitat fragmentation Habitat fragmentation describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat), causing population fragmentation and ecosystem decay. Causes of habitat fragmentation include geological proces ...

caused by development and habitat modification. This lizard used to be found in all of the San Joaquin Valley and the adjacent foothills of southern California. The Blunt-nosed leopard lizard now only occupies a few, scattered, undeveloped plots of land on the floor of the San Joaquin Valley and in the foothills of the Coast Range. San Joaquin Valley is a desert experiencing an ecological shift due to invasive species of non-native annual grasses most likely spread by grazing cows. The blunt-nosed leopard lizard along with other small terrestrial vertebrates are declining due to the ecological changes of the San Joaquin Valley as it is hypothesized that the invasive plants are altering vegetative structure. Although cattle may have originally been a factor in the establishment of these invasive species of plants, it was discovered by David Germano et al. that continued grazing, in order to keep the spread of the grasses limited, allowed for an increase in population size of not only the blunt-nosed leopard lizard, but other suffering species of the Valley as well.

Sources

* Listed as Endangered (EN A1ce v2.3) *"''Gambelia sila'' ". ITIS (Integrated Taxonomic Information System). www.itis.gov. Retrieved on 10-26-2012. *CSU Stanislaus (2006), Endangered Species Recovery Program, Dept. of Biological Sciences, One University Circle, Turlock, California 95382. http://esrp.csustan.edu/publications/pubhtml.php?doc=sjvrp&file=chapter02K00.html. Retrieved on 10-26-2012. *Blunt-nosed Leopard Lizard (''Gambelia sila''). Arkive.com. Wildscreen, n.d. Web. 24 Oct. 2012

*Germano, David J. (2007). "Food Habits of the Blunt-Nosed Leopard Lizard". ''Southwestern Naturalist'' 52 (2): 318-23. BioOne. 6 Oct. 2010. Web. 24 Oct. 2012

*Germano DJ, Williams DF (1993). "Recovery of the blunt-nosed leopard lizard: past efforts, present knowledge, and future opportunities". ''Trans. West. Sec. Wildl. Soc.'' 28: 38-47. *Montanucci RR (1965). "Observations on the San Joaquin leopard lizard, ''Crotaphytus wislizenii silus'' Stejneger". ''Herpetologica'' 21: 270-283. * Robert C. Stebbins, Stebbins RC (1985). ''A Field Guide to Western Reptiles and Amphibians, Second Edition''. Boston: Houghton Mifflin Company. 336 pp. *Tollestrup K (1983). "The social behavior of two species of closely related leopard lizards, ''Gambelia silus'' and ''Gambelia wislizenii'' ". ''J. Tierpsychol.'' 62: 307-320. *United States Fish and Wildlife Service (1985). Blunt-nosed leopard lizard revised recovery plan. Portland, Oregon: U.S. Fish and Wildlife Service. 85 pp.