Panamint chipmunk
The Panamint chipmunk is a species of rodent in the squirrel family, Sciuridae. It is endemic to desert mountain areas of southeast California and southwest Nevada in the United States.
It is considered a species of least concern on the IUCN Red List due to its broad range, prevalence, and no known major threats. The Panamint chipmunk occurs in pinyon pine-juniper woodlands in bushes, boulders, and on cliffs.
Environmentally, the Panamint chipmunks are a prey species that contributes to the diets of their predators, including birds, raptors, coyotes, foxes, and bobcats.
Description
Panamint chipmunks are medium-sized chipmunks with a head-and-body length of about 11–12 cm and a tail length of roughly 9–10 cm. Adults weigh between 74 and 105 g, with females on average somewhat larger than males. In summer, their fur is a bright golden or reddish-brown on the shoulders and sides with a grayish tinge on the anterior back. They have characteristic dark and light stripes on the back and face: five dark dorsal stripes divided by lighter stripes, which are bold on the upper back and diminish toward the rump. The core dorsal stripe is normally brown, while the peripheral stripes mix with the body coloration. The flanks are grayish, and the top of the head is a light gray with less dark facial striping. In winter, the coat becomes longer, silkier, and more yellowish, with overall paler patterns. The pelage coloration and pattern assist hide the animal against the rocky outcrops and scrub of its habitat.Taxonomy
The Panamint chipmunk is a member of the tribe ground squirrels and is one of 23 species of western chipmunks within the genus Neotamias. Clinton Hart Merriam initially classified it as Tamias panamintinus in 1893. Western chipmunks were once categorized in the genus Eutamias, but contemporary taxonomists typically group them within Neotamias, occasionally as a subgenus of Tamias. Two subspecies of the Panamint chipmunk are identified: the nominate T. p. panamintinus and T. p. acrus. ''T. p. panamintinus, located in the Panamint and neighboring mountains, is somewhat larger and lighter, exhibiting tawny sides and a grayer crown. In contrast, T. p. acrus, originating from the Kingston and Clark Mountains, is smaller, featuring deeper brownish sides and a more slender skull. Genetic research indicates that the Panamint chipmunk is closely related to the least chipmunk and the long-eared chipmunk within the western chipmunk classification.Distribution and habitat
The Panamint chipmunk is exclusively located in southwestern North America, particularly in regions of eastern California and western Nevada. Its distribution is sporadic, limited to hilly regions. In California, it is found in the eastern slopes of the southern Sierra Nevada and in other desert mountain ranges, including the Panamint, Argus, Inyo, White, Clark, Granite, Kingston, Providence, and Mescal ranges. The species was initially identified in the Panamint Range, currently part of Death Valley National Park, and it also resides in the Mojave National Preserve and other elevated desert regions. People live in the mountainous parts of Nevada's southwestern part, such as the Spring Mountains, the Sweetwater, Wassuk, Grapevine, Silver Peak, and Excelsior ranges. The height varies from roughly 1,300 to 2,700 meters above sea level. The Panamint chipmunk has a strong preference for pinyon-juniper woods that grow in rocky areas throughout this range. It is usually found on dry, rocky slopes with lots of granite formations, boulder groups, and cliff ledges. The soil is thin, and the plants are mostly scrub and scattered pinyon pine and juniper trees.This species thrives in conditions that are too hot and dry for many other chipmunks. For example, it lives in sun-drenched talus and rock formations in desert highlands where there isn't much shade. It often lives in small spaces between rocks and in underground tunnels, where it can breed and stay safe from extreme temperatures. Panamint chipmunks are mostly not found in wide flats or thick sagebrush plains. Also, in certain places where they live, they live next to the least chipmunk, which prefers sagebrush flats that the Panamint chipmunk does not like. It is thought that the different ways these species use their habitats show that they have different levels of temperature tolerance and specialization for certain types of habitats. N. panamintinus is a specialist of rocky mountains near the Mojave Desert, thus it needs a habitat that has cliffs or rocks next to pinyon and juniper trees that make nuts.
Genome and genetics
The Panamint chipmunk, similar to other chipmunks, possesses a diploid chromosome count of 2n = 38 and displays the "karyotype B" chromosomal configuration typical of several western chipmunk species. No complete genome sequence has been published for this species. Nonetheless, molecular data, such as mitochondrial DNA, have been utilized to deduce its evolutionary relationships. Genetic research indicate that N. panamintinus has recent common ancestors with several other Neotamias chipmunks, including N. quadrimaculatus and N. minimus.Behavior
Panamint chipmunks are diurnal, engaging in foraging and navigating among rocks and plants throughout the daylight hours. They often stay close to protection, such as rocky outcrops and trees, and rarely enter open, exposed regions. Individuals are frequently seen positioned on boulders or logs while consuming seeds or monitoring for threats.This chipmunk is predominantly solitary outside the breeding season, although exhibits social interactions within family groups, especially in terms of maternal care for the young. It demonstrates territorial behavior: adults establish and protect home territories, possibly measuring approximately one hectare or fewer, similar to related chipmunks. Intraspecific aggressiveness, characterized by fights or chases among Panamint chipmunks, has been observed in all seasons, with heightened frequency during the spring breeding time. Male individuals may vie for access to females, while both genders may safeguard optimal feeding or nesting territories. Although Panamint chipmunks can endure elevated temperatures, they limit their activity during the most severe conditions. They are classified as facultative hibernators; on extremely cold winter days or periods of snow cover, they remain in their burrows in a state of torpor. They do not undergo prolonged, continuous hibernation like certain ground squirrels; rather, they estivate or hibernate intermittently, contingent upon climatic conditions and food supply. During temperate winter days, they may surface to forage and store food for consumption when seeking refuge during winter storms. During the sweltering summer months, they may seek refuge in shade or remain inactive during the hottest part of the day, as crepuscular activity peaks are typical among desert mice.
Panamint chipmunks convey messages by vocalizations and body language characteristic of chipmunks. They produce bird-like chirps and trilling alarm cries, employing chatters or whistles during courting or territorial conflicts. Neonate chipmunks can vocalize within 24 hours of birth, and their calls are crucial for mother-offspring interactions. The Panamint chipmunk exhibits behavior adapted to a hard environment: it remains close to shelter, forages opportunistically, and enters torpor to endure cold or drought conditions.
Diet
It feeds mainly on seeds and fruits, particularly pinyon nuts and juniper berries, but also eats willow catkins, green vegetation, insects, lichens, bark, and occasionally carrion. In captivity, individuals consumed about 4–5.5 g of food daily and were observed caching seeds for later use.Reproduction
Panamint chipmunks reproduce once a year, in a seasonal cycle. The breeding season takes place in the spring, from March to May. During this time, females become receptive and mating occurs. During this time, both men and females are looking for companions, and as we have seen, males often fight with each other over partners. It is thought that the species has a polygynous mating system, which means that one male can mate with more than one female. This is typical among chipmunks, although there haven't been many detailed field studies.The gestation phase lasts 36 days or more post-conception. Parturition takes place in late spring, specifically from late May to early June across the majority of its distribution. Each female typically produces a litter of approximately 3 to 6 pups, with a recorded range of 3 to 9 offspring each litter. Newborn Panamint chipmunks are altricial, characterized by being born hairless, blind, and wholly reliant on the mother. The mother resides with her offspring in a protected burrow or rocky fissure supplying nourishment and warmth. Males do not engage in the rearing of offspring. After mating, only the female assumes parental responsibilities.
The puppies develop rapidly during the early summer. They are weaned at approximately 4 to 5 weeks of age, by which point they possess fur, their eyes are open, and they start to resemble little adults. The young typically first emerge from the natal burrow at approximately 5 to 6 weeks of age, going above ground in mid-summer, generally by July. At this stage, they are completely mobile and begin foraging in conjunction with the mother. The juvenile chipmunks attain independence by the conclusion of their inaugural summer; moreover, akin to other chipmunks, the young are likely to disperse or, at the very least, cache their own sustenance and enter solitary winter dormancy in their first year. Both females and males can attain sexual maturity by the subsequent breeding season and reproduce in their initial spring as yearlings.