San Esteban Chuckwalla
Encyclopedia
The San Esteban chuckwalla (Sauromalus varius) (also known as the Piebald chuckwalla or Pinto chuckwalla) is a species
of chuckwalla
belonging to the Iguanidae
family endemic to San Esteban Island
in the Sea of Cortés. It is the largest of the five species of chuckwallas and the most endangered.
name, Sauromalus, is a combination of two Ancient Greek
words:σαῦρος (sauros) meaning "lizard
". and ομαλυς (omalus) meaning "flat". Its specific name varius is Latin for "speckled," in reference to the chuckwalla's mottled coloration. It was first described by American herpetologist Mary C. Dickerson in 1919.
The common name chuckwalla derives from the Shoshone
word "tcaxxwal" or Cahuilla
"caxwal", transcribed by Spaniards
as "chacahuala". The Seri people named originally the island for this species: Coftécöl lifa or the Peninsula of the Giant Chuckwalla.
in the Sea of Cortés. While it is abundant on this small island, it occurs naturally nowhere else and is protected under the Endangered Species Act
. At one time the Seri translocated populations of this lizard to other islands in the Sea of Cortés as a food item, however, none of these populations have survived beyond the original population found on San Esteban.
Males are seasonally and conditionally territorial; an abundance of resources tends to create a hierarchy based on size, with one large male dominating the area's smaller males. Chuckwallas use a combination of colour and physical displays, namely "push ups", head-hobbing, and gaping of the mouth to communicate and defend their territory (see animal communication
).
Chuckwallas are diurnal
animals and as they are ectotherm
ic, spend much of their mornings and winter days basking in the sun. These lizards are well adapted to desert conditions; they are active at temperatures of up to 102°F (39°C).
Mating occurs from April to July, with 5–16 eggs laid between June and August. The eggs hatch in late September. San Esteban chuckwallas may live for 25 years or more.
and cholla
cacti which form the staple of their diet as the chuckwalla is primarily herbivorous
. Chuckwallas also feed on leaves, fruit and flowers of annual
s, perennial plant
s, and even weed
s; insect
s represent a supplementary prey if eaten at all.
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The San Esteban chuckwalla is the largest species of chuckwalla reaching 61 centimetres (24 in) in body length, 76 centimetres (29.9 in) overall length and weighing up to 1.4 kilograms (3.1 lb). It is considered a textbook example of island gigantism
as it is 3 to 4 times the size of its mainland counterparts. Their skin is gray with tan to yellow patches over their entire bodies, and their faces are gray to black. Females are duller in appearance with less patches. Their colorations provide almost perfect camouflage against some of their predators.
of Seri who once inhabited San Esteban Island referred to themselves as Coftécöl Comcáac, "People of the Giant Chuckwalla" and named the island for this species.
The San Esteban chuckwalla is an endangered species due to hunting from the Seri and the introduction of feral animals such as rat
s and mice
which prey upon the chuckwalla's eggs and feral dogs and cats which prey upon the lizards. Due to these factors and overcollection from the pet trade, the species was declared an Appendix I animal under CITES.
There is an in situ
chuckwalla captive breeding program in Punta Chueca
, a Seri village on San Esteban. A successful ex situ
program has also been in place at the Arizona-Sonora Desert Museum
since 1977. The species is present in private collections and is often crossbred with the smaller Angel Island chuckwalla
.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of chuckwalla
Chuckwalla
Chuckwallas are large lizards found primarily in arid regions of the southwestern United States and northern Mexico. Some are found on coastal islands...
belonging to the Iguanidae
Iguanidae
Iguanidae is a family of lizards, composed of iguanas and related species.-Classification of Iguanidae:Two different classification schemes have been used to define the structure of this family. These are the "traditional" classification and the classification presented by Frost et al. .Frost et...
family endemic to San Esteban Island
San Esteban Island
San Esteban Island is a small island in the Gulf of California, Mexico, located to the southwest of Tiburón Island. It is part of the Municipality of Hermosillo in Sonora, and has a land area of 39.773 km² , the 15th-largest island in Mexico. It is located in the Sea of Cortés...
in the Sea of Cortés. It is the largest of the five species of chuckwallas and the most endangered.
Taxonomy and etymology
The genericGenera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
name, Sauromalus, is a combination of two Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
words:σαῦρος (sauros) meaning "lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
". and ομαλυς (omalus) meaning "flat". Its specific name varius is Latin for "speckled," in reference to the chuckwalla's mottled coloration. It was first described by American herpetologist Mary C. Dickerson in 1919.
The common name chuckwalla derives from the Shoshone
Shoshone
The Shoshone or Shoshoni are a Native American tribe in the United States with three large divisions: the Northern, the Western and the Eastern....
word "tcaxxwal" or Cahuilla
Cahuilla
The Cahuilla, Iviatim in their own language, are Indians with a common culture whose ancestors inhabited inland areas of southern California 2,000 years ago. Their original territory included an area of about . The traditional Cahuilla territory was near the geographic center of Southern California...
"caxwal", transcribed by Spaniards
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
as "chacahuala". The Seri people named originally the island for this species: Coftécöl lifa or the Peninsula of the Giant Chuckwalla.
Distribution and habitat
The San Esteban chuckwalla is endemic to San Esteban IslandSan Esteban Island
San Esteban Island is a small island in the Gulf of California, Mexico, located to the southwest of Tiburón Island. It is part of the Municipality of Hermosillo in Sonora, and has a land area of 39.773 km² , the 15th-largest island in Mexico. It is located in the Sea of Cortés...
in the Sea of Cortés. While it is abundant on this small island, it occurs naturally nowhere else and is protected under the Endangered Species Act
Endangered Species Act
The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...
. At one time the Seri translocated populations of this lizard to other islands in the Sea of Cortés as a food item, however, none of these populations have survived beyond the original population found on San Esteban.
Behavior and reproduction
Harmless to humans, these large lizards are known to run from potential threats. When disturbed, the chuckwalla will wedge itself into a tight rock crevice, gulp air, and inflate its body in order to entrench itself.Males are seasonally and conditionally territorial; an abundance of resources tends to create a hierarchy based on size, with one large male dominating the area's smaller males. Chuckwallas use a combination of colour and physical displays, namely "push ups", head-hobbing, and gaping of the mouth to communicate and defend their territory (see animal communication
Animal communication
Animal communication is any behavior on the part of one animal that has an effect on the current or future behaviour of another animal. The study of animal communication, is sometimes called Zoosemiotics has played an important part in the...
).
Chuckwallas are diurnal
Diurnal animal
Diurnality is a plant or animal behavior characterized by activity during the day and sleeping at night.-In animals:Animals that are not diurnal might be nocturnal or crepuscular . Many animal species are diurnal, including many mammals, insects, reptiles and birds...
animals and as they are ectotherm
Ectotherm
An ectotherm, from the Greek εκτός "outside" and θερμός "hot", refers to organisms that control body temperature through external means. As a result, organisms are dependent on environmental heat sources and have relatively low metabolic rates. For example, many reptiles regulate their body...
ic, spend much of their mornings and winter days basking in the sun. These lizards are well adapted to desert conditions; they are active at temperatures of up to 102°F (39°C).
Mating occurs from April to July, with 5–16 eggs laid between June and August. The eggs hatch in late September. San Esteban chuckwallas may live for 25 years or more.
Diet
Chuckwallas prefer dwelling in lava flows and rocky areas with nooks and crannies available for a retreat when threatened. These areas are typically vegetated by creosote bushCreosote bush
Larrea tridentata is known as Creosote bush as a plant, chaparral as a medicinal herb, and as "gobernadora" in Mexico, Spanish for "governess," due to its ability for inhibiting the growth of nearby plants to have more water. In Sonora, it is more commonly called "hediondilla." It is a flowering...
and cholla
Cholla
Cholla can refer to the following things:* Cholla cacti, a genus of cyllindrically-stemmed cacti* Cholla , a painting horse born in Nevada* Jeolla , former Korean province...
cacti which form the staple of their diet as the chuckwalla is primarily herbivorous
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
. Chuckwallas also feed on leaves, fruit and flowers of annual
Annual plant
An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...
s, perennial plant
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
s, and even weed
Weed
A weed in a general sense is a plant that is considered by the user of the term to be a nuisance, and normally applied to unwanted plants in human-controlled settings, especially farm fields and gardens, but also lawns, parks, woods, and other areas. More specifically, the term is often used to...
s; insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s represent a supplementary prey if eaten at all.
Description
Island gigantism
Island gigantism or insular giantism is a biological phenomenon in which the size of animals isolated on an island increases dramatically in comparison to their mainland relatives....
as it is 3 to 4 times the size of its mainland counterparts. Their skin is gray with tan to yellow patches over their entire bodies, and their faces are gray to black. Females are duller in appearance with less patches. Their colorations provide almost perfect camouflage against some of their predators.
Human contact
The Seri considered this species of chuckwalla an important food item due to its large size. The tribeTribe
A tribe, viewed historically or developmentally, consists of a social group existing before the development of, or outside of, states.Many anthropologists use the term tribal society to refer to societies organized largely on the basis of kinship, especially corporate descent groups .Some theorists...
of Seri who once inhabited San Esteban Island referred to themselves as Coftécöl Comcáac, "People of the Giant Chuckwalla" and named the island for this species.
The San Esteban chuckwalla is an endangered species due to hunting from the Seri and the introduction of feral animals such as rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...
s and mice
MICE
-Fiction:*Mice , alien species in The Hitchhiker's Guide to the Galaxy*The Mice -Acronyms:* "Meetings, Incentives, Conferencing, Exhibitions", facilities terminology for events...
which prey upon the chuckwalla's eggs and feral dogs and cats which prey upon the lizards. Due to these factors and overcollection from the pet trade, the species was declared an Appendix I animal under CITES.
There is an in situ
In-situ conservation
In-situ conservation is on-site conservation or the conservation of genetic resources in natural populations of plant or animal species, such as forest genetic resources in natural populations of tree species...
chuckwalla captive breeding program in Punta Chueca
Punta Chueca
Punta Chueca is a Seri town located on the Gulf of California in the Mexican state of Sonora. It is located 16 miles north of the fishing and tourist town of Bahía de Kino...
, a Seri village on San Esteban. A successful ex situ
Ex-situ conservation
Ex-situ conservation means literally, "off-site conservation". It is the process of protecting an endangered species of plant or animal outside of its natural habitat; for example, by removing part of the population from a threatened habitat and placing it in a new location, which may be a wild...
program has also been in place at the Arizona-Sonora Desert Museum
Arizona-Sonora Desert Museum
The Arizona-Sonora Desert Museum is a museum and zoo founded in 1952 and located in Tucson, Arizona. It contains a museum and two miles of walking paths on of this property, and is one of the most visited attractions in Tucson...
since 1977. The species is present in private collections and is often crossbred with the smaller Angel Island chuckwalla
Angel Island Chuckwalla
The Angel Island chuckwalla is a species of chuckwalla belonging to the Iguanidae family endemic to Isla Ángel de la Guarda in the Sea of Cortés...
.