In southern California, Crotalus ruber (the Red Diamond Rattlesnake) can be found in San Bernadino, Los Angeles, Orange, Riverside, Imperial, and San Diego counties. In Baja California, it can be found from the U.S. border throughout the peninsula, and on the islands of Angel de la Guarda, Danzante, Monserrate, Pond, San Jose, San Lorenzo de Sur, San Marcos, Cedros, and Santa Margarita (Ernst and Ernst 2012). (Ernst and Ernst, 2012)
Red diamond rattlesnakes live in desert or coastal scrublands, chaparral, pine-oak woods, tropical deciduous forests, and occasionally in grasslands and other cultivated areas (Campbell and Lamar 2004, Ernst and Ernst 2012). They are most commonly found in areas with chaparral and sage scrub, low elevation, and high winter precipitation (Ernst and Ernst 2012). Particularly in the southern part of the range, Red Diamond Rattlesnakes prefer habitats with rocky outcroppings or heavy brush (Campbell and Lamar 2004). These are important for use as hibernacula (Brown et al. 2008). Studies suggest that (Brown, et al., 2008; Campbell and Lamar, 2004; Ernst and Ernst, 2012; Thomson, et al., 2016)prefers to avoid developed areas and are reluctant to cross roads (Thomson et al. 2016).
Some authors recognize at least four subspecies; see Ernst and Ernst (2012) for descriptions of these. In the northern part of range these snakes are brick-red, reddish-gray, pinkish-brown, or tan dorsally. In southern Baja California, they are often yellowish-brown to olive-brown dorsally. Reddish-brown diamonds with a light border (which may be reduced on the lateral edges) are present on the dorsal side of the body, and may be separated by white or tan on the anterior half to two-thirds of the body. There may be 20-42 diamonds, though 33-35 is usual. A row of small, dark diamonds may be present laterally. Dorsal scales are keeled and pitted, excepting lateral rows 1-2. The most proximal rattle segment is black, and the tail has 2-7 black rings just anterior to the rattle (Ernst and Ernst 2012). In mainland populations, the rattle is well-developed, with up to 13 segments (Klauber 1982, Campbell and Lamar 2004). However, individuals from Isla San Lorenzo de Sur may lose rattle segments during shedding; about half of this population lack a rattle (Campbell and Lamar 2004). The venter has no markings, and is white to cream in color. The anal plate is undivided (Ernst and Ernst 2012).
The head is triangular, reddish, lacks a dorsal pattern, and has a diagonal dark stripe extending from the bottom edge of the eye to the corner of the mouth (Ernst and Ernst 2012, Thomson et al. 2016). The stripe has a light-colored border anteriorly; a posterior border may or may not be present (Ernst and Ernst 2012). Heat-sensing pits are located on either side of the head, between the nostrils and eyes. The neck is very thin (Thomson et al. 2016).
The confirmed maximum body length is 162.5 cm, though unconfirmed reports state the rattlesnakes may reach 190.5 cm. Island dwarfism has been observed; island snakes are usually less than 90 cm, while mainland snakes often exceed 100 cm (Ernst and Ernst 2012). Males are larger than females (Dugan and Hayes 2012). (Campbell and Lamar, 2004; Dugan and Hayes, 2012; Ernst and Ernst, 2012; Klauber, 1982; Thomson, et al., 2016)
Courtship and mating in the wild occur from March through May, though in captivity mating can occur year-around (Campbell and Lamar 2004, Ernst and Ernst 2012). Males will actively search for females, leading to an increased home range during the breeding season (Dugan et al. 2008). Following courtship, mating usually lasts from six to twelve hours, though it can sometimes last less than an hour or longer than twenty-two hours (Klauber 1982). Fertilization is accomplished via insertion of one (of two) hemipenes, as in all squamates. It is believed that sperm storage does not occur, though more research may be necessary (Brown et al. 2008). (Brown, et al., 2008; Campbell and Lamar, 2004; Dugan, et al., 2008; Ernst and Ernst, 2012; Klauber, 1982)
Gestation lasts from 141 to 190 days. Females give birth to litters of 3 to 20 young from July to December, usually in August or September (Campbell and Lamar 2004, Ernst and Ernst 2012). Juveniles resemble adults in patterning, though the coloration is duller and more grayish. Neonates measure 28 to 35 cm long at birth (Shupe 2011). Hybridization has occured with Crotalus oreganus helleri, but seem to be more common in captivity than in the wild (Klauber 1982). (Brown, et al., 2008; Campbell and Lamar, 2004; Dugan, et al., 2008; Ernst and Ernst, 2012; Klauber, 1982; Shupe, 2011)
Females must invest considerable energy and resources in yolking eggs and carrying the developing young prior to birth. No post-birth parental care has been observed for Red Diamond Rattlesnakes; neonates have only been observed with their mother immediately after birth (Brown et al. 2008). (Brown, et al., 2008)
An adult, wild-caught male lived an additional 19 years and 2 months as a captive. A zoo specimen lived 14 years 6 months. (Ernst and Ernst, 2012)
avoids severe heat and tends to be active at cooler temperatures. Thus, they are usually nocturnal from late spring through summer, and diurnal during cooler parts of the year. Most activity above ground occurs from April through June. The activity periods may vary depending on the surrounding environment; coastal populations tend to be more diurnal than desert populations (Campbell and Lamar 2004). These rattlesnakes typically hibernate from October or November through February or March (Ernst and Ernst 2012). Communal hibernacula may or may not be used (Brown et al. 2008, Dugan et al. 2008).
Red Diamond Rattlesnakes swim in freshwater lakes, reservoirs, and the Pacific Ocean, sometimes frightening fishermen (Klauber 1982, Ernst and Ernst 2012). However, it seems that they do not swim voluntarily, but are rather washed into rivers by heavy rainfall (Lillywhite 2014). These snakes are also capable of climbing into low bushes, cacti, and trees, where they may pursue arboreal prey such as birds and small mammals.
Maleparticipate in ritualized combat "dances" which may last for longer than 15 minutes. These events occur most often during the breeding season. Combat is essentially a shoving match; the anterior portion of the body is raised and twisted around the opposing male (Campbell and Lamar 2004). The male which is successful in pinning the other to the ground is victorious. It was originally believed that the dances were involved in courtship; it is now thought that they are used in establishing dominance (Ernst and Ernst 2012).
The size of the home range varies by time of year. During the warmer seasons when they are more active, an individual may have a home range of 0.3 to 6.2 hectares. During the winter, the size of the home range will be far smaller, perhaps 100 to 2600 square meters. Males have larger home ranges than females and desert populations have larger ranges than coastal populations (Dugan et al. 2008). (Dugan, et al., 2008; Ernst and Ernst, 2012)
Rattlesnakes as a group are famous for rattling their tails as a warning signal to potential threats (Greene 1997). The muscles in the tail are specialized to contract rapidly without fatigue. The shaker tail muscles can sustain a rate of 50 contractions per second for at least three hours, resulting in a sustained, high-frequency noise (Campbell and Lamar 2004). The rattle is not used outside of defensive purposes (Greene 1997). Though it has been suggested that rattles may be used for communication with conspecifics, the noises produced by rattles falls outside the hearing range of snakes (Lillywhite 2014).
In response to threats,individuals may also inflate the body and produce a long, sustained hiss. While hissing can serve as a basic warning signal, it is unlikely to encode any more complex information (Lillywhite 2014).
Red diamond rattlesnakes are primarily ambush predators and hunt during both day and night (Barbour and Clark 2012, Dugan and Hayes 2012). A foraging site is chosen using chemical and thermo-visual cues (Barbour and Clark 2012). The snake remains motionless, striking when a prey item comes in range and injecting venom. Mammalian prey is immediately released to avoid injury to the snake, and followed by scent, using the vomeronasal organ. Eventually the prey item succumbs to the venom and is consumed by the rattlesnake (Barbour and Clark 2012, Ernst and Ernst 2012). Occasionally they will eat carrion (Dugan and Hayes 2012, Ernst and Ernst 2012). Gravid females may abstain from feeding (Dugan and Hayes 2012).
Mammalian prey items are most common. Red diamond rattlesnakes consume white-tailed antelope squirrels, agile kangaroo rats, desert kangaroo rats, Merriam's kangaroo rats, California voles, desert woodrats, southern grasshopper mice, California pocket mice, California mice, Canyon mice, cactus mice, western harvest mice, western spotted skunks, Audubon's cottontails, brush rabbits, and Botta's pocket gophers. Reptilian prey items are less common: tiger whiptails, Cape spinytail iguanas, desert spiny lizards, granite spiny lizards, and Central Baja spiny lizards. Birds, such as California towhees, are consumed only rarely (Dugan and Hayes, 2012). (Barbour and Clark, 2012; Dugan and Hayes, 2012; Ernst and Ernst, 2012)
Large adult red diamond rattlesnakes are likely only threatened by humans and occasional predation by coyotes. However, smaller individuals, especially juveniles, may also be consumed by kingsnakes, great horned owls, hawks, raccoons, badgers, striped skunks, western spotted skunks, bobcats, cougars, dogs, gray foxes, and kit foxes (Ernst and Ernst 2012). (Ernst and Ernst, 2012)
In many habitats, red diamond rattlesnakes are top predators in their ecosystems. They have an important role in controlling prey populations, including many small mammals, lizards, and birds (Dugan and Hayes 2012, Corbit 2015). In addition to consuming woodrats, red diamond rattlesnakes sometimes use their nests as hibernacula (Brown et al. 2008). In some studies, a strong association has been observed between red diamond rattlesnakes, Opuntia cacti, and granite boulders. The boulders may provide hibernacula, while the cacti may provide protection from predators and be attractive to prey species (Brown et al. 2008). (Brown, et al., 2008; Corbit, 2015; Dugan and Hayes, 2012; Ernst and Ernst, 2012)
Rattlesnakes control small mammal populations, which can destroy crops and spread disease (Corbit 2015). (Corbit, 2015)
Red diamond rattlesnakes are considered a Priority 3 Species of Special Concern in California, due to the decimation of coastal and sage scrub habitats for urban development (Dugan and Hayes 2012, Thomson et al. 2016). (Campbell and Lamar, 2004; Ernst and Ernst, 2012; Thomson, et al., 2016)has been eliminated from approximately 20% of its historical range due to human development. Populations may be further threatened by persecution, road mortality, and shifts in fire regime and vegetation due to global climate change (Thomson et al. 2016).
Genetic and morphology studies show that Crotalus atrox group of rattlesnakes (which includes Crotalus adamanteus, Crotalus atrox, Crotalus catalinensis, and Crotalus tortugensis). This species is apparently most closely related to Crotalus catalinensis. (Ernst and Ernst, 2012)is a member of the
Amber Suto (author), Michigan State University, James Harding (editor), Michigan State University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
flesh of dead animals.
Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.
uses smells or other chemicals to communicate
active at dawn and dusk
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
(as keyword in perception channel section) This animal has a special ability to detect heat from other organisms in its environment.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
young are relatively well-developed when born
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