Sonoma chipmunk
| Sonoma chipmunk | ||||||||||||
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Juvenile (left) and adult specimen (right) |
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| Tamias sonomae | ||||||||||||
| ( Grinnell , 1915) |
The Sonoma chipmunk ( Tamias sonomae , Syn .: Neotamias sonomae ) is a type of squirrel from the genus of chipmunks ( Tamias ). It occurs in two subspecies only in the northwest of the American state California north of San Francisco . It is a medium-sized chipmunk that, like other chipmunks, lives primarily in trees and bushes, where it feeds mainly on various plant seeds and fruits. The species is assigned to a relationship complex around the Townsend chipmunk ( Tamias townsendii ) and is very difficult to distinguish from other species in this complex.
The species is classified as “not endangered” by the International Union for Conservation of Nature and Natural Resources (IUCN) and the populations are considered stable.
features
general characteristics
The Sonoma chipmunk reaches an average length of 22.0 to 27.7 centimeters. The head-torso length is given for individual individuals with about 13.3 to 13.9 centimeters, the tail length with about 10.6 to 11.6 centimeters, and the weight is about 70 grams. The ear length is 15 to 23 millimeters and the hind foot length 33 to 37 millimeters. The animals show no sexual dimorphism and correspond in size, animals of the subspecies Tamias sonomae alleni are, however, somewhat smaller than individuals of the nominate form .
The back color of the animals is red-brown in summer, from July to September, and as with other species of the genus, there are several dark back stripes on the back, which are separated by lighter stripes and delimited from the sides of the body. The head is red-brown with smoky gray and cinnamon-colored speckles, the dark facial stripes are dark red-brown to blackish red-brown, partially interspersed with cinnamon. The shoulders, the front back and the two middle light stripes are sand-colored to ocher-sand-colored and the stripes are interspersed with white in the rear part. The two outer light stripes are interspersed with matt white and sand-colored. The dark back stripes are black, rarely dark red-brown, and the dark side stripes are dark-red-brown and often only indistinctly demarcated at the edge from the dark-sand colored flank. The hull is ocher-sand colored and interspersed with a cinnamon-colored tone and the hips are red-brown with a cinnamon-colored tint and partly gray-white speckles. The feet are sand to cinnamon-colored, the hind feet partially washed in reddish brown. The tail is washed in red-brown to black and lighter sand-brown on the upper side, and is framed sand-colored and darker on the underside. The ventral side is grayish-white and washed with a pale ocher-sand-colored shade. The coat change to winter coat takes place in October. The winter color corresponds to the summer color, but is overall darker, the belly side is creamy white in winter. Compared to the nominate form, the subspecies Tamias sonomae alleni is slightly smaller and the back color is generally a bit darker over the entire year. The dark back stripes are blacker and more pronounced and the light stripes on the flanks are more sand-colored, on the face there is no olive-green tint.
The Sonoma chipmunk differs from the yellow spruce chipmunk mainly in its size and red color. Color it closely resembles the Townsend-chipmunk ( Tamias townsendii ) and other types of townsendii -Verwandtschaftskomplexes and can be confused with it easily. It is slightly larger than the Townsend squirrel with longer limbs, a longer, wider, and bushier tail, and longer ears. In addition, it is paler and more reddish in basic color and it has a species-typical white delimitation on the tail and a reddish area on the underside of the tail, which is paler in comparison to other species and not darker in the front area. In winter fur, the cheeks are gray instead of brown, the ears are only sparsely hairy and monochrome in summer fur.
Features of the skull and skeleton
The skull of the species is long and narrow with a maximum width making up about 54% of the total length. The nominate-shaped skull has a total length of 38.0 to 39.7, on average 38.7 millimeters, in the area of the zygomatic arches the width is 19.4 to 21.3, on average 20.3 millimeters. The skull of Tamias sonomae alleni is slightly smaller. Compared to other species, the skull is longer and narrower with closer fitting zygomatic arches. The skull is long and flattened, the muzzle region (rostrum) is deep, and the nasal bones are separated by a small knot at the tip above the incisors. The foramina incisiva are shorter than in other species, the posterior end of the palatine bone is thickened and ends in a short instead of a long spine in other species. Further characteristics typical of the species relate primarily to the structure and development of the hyoid bone (os hyoideum).
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The animals possess as all the subgenus Neotamias one to an associated species in the upper jaw and the lower jaw half per incisor tooth formed incisor (incisor) to which a tooth gap ( diastema follows). This is followed by two premolars in the upper jaw and one premolar and three molars in the lower jaw . In total, the animals have a set of 22 teeth. The upper incisors are strongly bent back compared to other species, the premolars and molars are only small.
Like other chipmunks , the males have a penis bone (bacculum) that is around 3.0 to 3.3 millimeters long. It has a very thin shaft and a flat keel that makes up about 10% of the tip. The angle between the shaft and the tip is 130 ° and the distal end of the shaft is slightly compressed laterally. The female counterpart, the clitoral bone (Baubellum), is long and thin and forms a wide U-shape from the base and shaft. It has a basal length of 0.5 to 1.1 millimeters, which corresponds to the length of the shaft. The angle between the shaft and the point is 150.4 ° and the point is 0.4 to 0.7 millimeters long with a very short but visible keel.
Genetic traits
The genome of Sonoma strip croissant is like the other chipmunks from 38 chromosomes (2n = 38). These are four pairs of large metacentric, six pairs of large submetacentric, four pairs of large acrocentric, one pair of small metacentric and three pairs of small acrocentric chromosomes. The X chromosome is submetacentric, the Y chromosome acrocentric. Within the genus, it is assigned to the type B karyotype.
distribution and habitat
The Sonoma chipmunk is only found in the northwest of the American state of California north of San Francisco . The distribution area ranges from Siskiyou County to San Francisco Bay , with the animals occurring at altitudes below 1800 meters.
The vegetation zones of the habitat range from the upper Sonoran zone, which is characterized by steppe-like vegetation, to the wooded transition zone. In the coastal area, the animals live mainly in open forest stands of the coastal redwood ( Sequoia sempervirens ) and in dry stands of the yellow pine ( Pinus ponderosa ), the white pine ( Pinus sabiniana ), the incense cedar ( Calocedrus decurrens ), the American strawberry tree ( Arbutus) menziesii ) and bushy oak trees ( Quercus ), for example in the chaparral . In addition, the species occurs along rivers and open bushes and in stocks of the Colorado fir ( Abies concolor ) and the magnificent fir ( Abies magnifica ). The animals usually avoid young forests and felling areas.
The Sonoma chipmunk comes in parts of its distribution area in Northern California sympatric with the yellow spruce chipmunk ( Tamias amoenus ) and the yellow-cheeked chipmunk ( Tamias ochrogenys ), the Allen chipmunk ( Tamias senex ) and the Siskiyou chipmunk ( Tamias siskiyou ), which together be assigned to the kinship group of the townsendii complex with him . These occurrences are mainly due to the interlocking of the mountain ranges and thus the specific vegetation in the transition areas; While the three species mentioned prefer the boreal spruce forests with Douglas fir and Colorado fir ( Abies concolor ), the Sonoma chipmunk lives in mixed forest areas characterized by Colorado fir, yellow pine ( Pinus ponderosa ) and California black oak ( Quercus kelloggii ). Compared to the Merriam chipmunk ( Tamias merriami ), the distribution area is delimited by the San Francisco Bay and the San Pablo Bay and the grassland in between. It is separated from the range of the long-eared chipmunk ( Tamias quadrimaculatus ) in the Sierra Nevada by the approximately 60 kilometers wide region of Lassen Peak , in which both species do not occur.
Way of life
The species is diurnal and lives on the ground as well as climbing in trees and bushes. The forest areas in which the species can be found include trees, shrubs, piles of wood and a layer of plant material on the forest floor. The animals feed like other chipmunks especially herbivores from seeds of coniferous trees, acorns and seeds, fruits and other plant parts of different plant species. A scientific study of the nutritional composition is not present, however, it is likely that the animals different plants use their habitat as a food source, such as the Prunus virginiana ( Prunus virginiana , known as chokecherry), Rock pears ( Amelanchier ) and garrya ( Garrya ). Other species of the genus also feed on leaves, flowers and herbs as well as mushrooms, insects and bird eggs. The foraging takes place mainly in the branches of smaller bushes. The animals often look for exposed positions on tree trunks, larger branches in the lower tree regions and on stones, as resting and observation places and to consume the food they have collected.
They communicate using very high-pitched, bird-like and species-specific calls that they emit when there is a potential threat. The females call more frequently than the males and there are significant differences in the calling frequency of younger and older animals, pregnant and lactating females, males willing to mate and other subgroups within the populations. The animals call out in the form of clusters of calls ("bursts") with several individual calls ("chips") from the branches of trees and bushes and also from the ground. They can do 10 to over 80 bursts with 50 to more than 100 chips per minute eject. The calls form a V-shape in the sonagram , in which the pitch first decreases and later increases again; in this they differ from all related species. In response to the calls, the animals usually quickly retreat deeper into the branches of trees or bushes or into piles of wood and other hiding places, where they then remain calm.
Reproduction and development
The mating season for this species is in spring and the females usually only have one litter per year. In lower altitudes, the mating season begins much earlier than in the higher elevations and the females of the lower elevations can ovulate several weeks before those of the higher elevations. In the males, the testicles swell during the mating season and migrate from the loins into an outer scrotum from December to June ; in late March, the testicles reach their maximum length of 13 to 16.5 millimeters. During the period in which the males are able to reproduce, they actively migrate into the territories with females ready to mate and compete with other males willing to mate.
The young are also born much earlier in the lowlands than in the highlands. The gestation period is around 30 to 31 days and the young are born in spring. The litter consists of three to five young animals on average and is suckled by the mother for 39 to 45 days, even if the young animals leave the nest during the day. The females look after the offspring alone and the female pups often stay with the mother after weaning, while the males spread out. It is assumed that kinship groups of female animals are formed through this behavior, which also causes the more frequent alarm calls to the female animals as a result of relatives selection for the protection of closely related individuals. The sex ratio of the animals after birth and when leaving the nest is around 1: 1, but changes in favor of the females by the first autumn. This is attributed to the different distribution strategies of the male and female young animals after leaving the nest. Even in the first spring after wintering, the young females outnumber the young males, but after the first reproduction the sex ratio in the following autumn is again around 1: 1 due to the increased mortality of the females during their first births and rearing. In older age females again predominate, while the mortality of males, especially between the ages of three to five years, is significantly higher than that of females.
Ecological importance, predators and parasites
The only proven predator of Sonoma chipmunk the Red-tailed Hawk ( Buteo jamaicensis ), moreover, but also other birds of prey and predators potential predators. As parasites are two types of animal lice ( Hoplopleura arboricola and Neohaematopinus pacificus ) and the nymphs of different ticks ( Dermacentor occidentalis , Ixodes pacificus and Ixodes spinipalpis ). Infections with the pathogen of the plague , Yersinia pestis , as well as the pathogen of Lyme borreliosis , Borrelia burgdorferi , for which rodents of the region are relevant as potential reservoir hosts, have not been detected in the Sonoma chipmunk. In contrast, Anaplasma phagocytophilum , the tick-borne pathogen causing human granulocytic anaplasmosis and canine anaplasmosis, was identified in several Sonoma chipmunks.
Like other species of the genus, the Sonoma chipmunk plays an essential role in the sowing and distribution of plant seeds and in the spread of mycorrhizal spores through its diet and the creation of supplies .
Systematics
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Possible relationship of the
Sonoma chipmunk
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The Sonoma chipmunk is classified as an independent species within the genus of chipmunks ( Tamias ), which consists of 25 species. The first scientific description comes from the American zoologist Joseph Grinnell from 1915, who described it as Eutamias sonomae based on individuals from the region west of Guerneville , Sonoma County , California and named it after the county as the place where it was found. The animals came from the collection of the California Museum of Vertebrate Zoology in Berkeley , whose first director was Grinnell.
In 1985 the species was revised by Levenson et al. slammed with all other chipmunks of the genus Tamias . Within this, the Sonoma chipmunk is assigned to the subgenus Neotamias , together with most of the other species , which is also discussed as an independent genus. In some cases it was considered a subspecies of the Townsend chipmunk ( Tamias townsendii ), but is now assigned to a species group known as the townsendii group, which contains seven other species in addition to the Sonoma and Townsend chipmunks: T. senex , T. ochrogenys , T. siskiyou , T. merriami , T. quadrimaculatus , T. obscurus and T. dorsalis . Within this kinship group, based on molecular biological data, the Sonoma chipmunk is considered to be a sister species of the Allen chipmunk ( Tamias senex ) and both are considered to be the sister group of the Townsend chipmunk. Alternatively, the Sonoma chipmunk is considered to be a sister species of a kindred of the Townsend chipmunk, Allen chipmunk, and Siskiyou chipmunk ( Tamias siskiyou ).
Within the species, together with the nominate form, two subspecies are distinguished:
- Tamias sonomae sonomae (Grinnell, 1915) : nominate form; occurs in the entire distribution area and is slightly larger and brighter than Tamias sonomae alleni .
- Tamias sonomae alleni Howell , 1922 : lives only in the extreme southwest of the distribution area near San Francisco Bay . The subspecies is slightly smaller and darker than the nominate form. The form was described in 1922 by Arthur H. Howell as Eutamias townsendii alleni and thus as a subspecies of the Townsend chipmunk on the basis of a male individual from Inverness in Marin County , California; it is named after Joel Asaph Allen . The type of Allen was originally assigned to the subspecies Eutamias townsendii hindsii , but after this was synonymous with Eutamias townsendii townsendii , Howell described the new subspecies on the basis of the specimen.
Status, threat and protection
The Sonoma chipmunk is classified as Least Concern (LC) by the International Union for Conservation of Nature and Natural Resources (IUCN) and the populations are considered stable. This is justified by the relatively large distribution area of more than 20,000 km 2 and the regular occurrence; there are no known risks to the existence of the plant.
Very few specific studies are available on the Sonoma chipmunk and the very small distribution area with different key habitats; therefore it is unknown to what extent anthropogenic influences negatively affect the species. There is a potential risk due to the very small distribution area in which major changes in habitat could have a strong impact on the total population of the species.
supporting documents
- ^ A b Lloyd G. Ingles: Mammals of the Pacific States: California, Oregon, Washington. Stanford University Press 1965, ISBN 0-8047-1843-1 , p. 181.
- ↑ a b c d e f g h Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012, ISBN 978-1-4214-0469-1 , pp. 340-341 .
- ↑ a b c d e f g J.L. Koprowski, EA Goldstein, KR Bennett, C. Pereira Mendes: Sonoma Chipmunk. In: Don E. Wilson, TE Lacher, Jr., Russell A. Mittermeier (Eds.): Handbook of the Mammals of the World: Lagomorphs and Rodents 1. (HMW, Volume 6) Lynx Edicions, Barcelona 2016, ISBN 978- 84-941892-3-4 , pp. 789-790.
- ↑ a b c d e f Samir Hasmukh Shah: Tamias sonomae (Sonoma chipmunk) in the Animal Diversity Web, 1999, accessed May 7, 2017.
- ↑ a b c d e f g h i j k l m n o p q r s t u v w x Troy L. Best : Tamias sonomae. ( Memento of March 15, 2016 in the Internet Archive ) Mammalian Species 444, 1993.
- ↑ Dallas A. Sutton: The Female Genital Bone of Chipmunks, Genus Eutamias. The Southwestern Naturalist 27 (4), Nov. 1982, pp. 393-402. ( JSTOR 3670714 )
- ↑ a b Neotamias sonomae in the IUCN Red List of Threatened Species 2015.4. Listed by: AV Linzey, NatureServe (G. Hammerson), 2008. Retrieved August 5, 2016.
- ^ A b Leonard R. Brand: The vocal repertoire of chipmunks (Genus Eutamias) in California. Animal Behavior 24 (2), 1976, pp. 319-335, doi : 10.1016 / S0003-3472 (76) 80040-1 .
- ↑ a b Stephen F. Smith: Alarm Calls, Their Origin and Use in Eutamias sonomae. Journal of Mammalogy 59 (4), 1978, pp. 888-893, doi : 10.2307 / 1380172 . JSTOR 1380172
- ^ Robert S. Lane, Richard N. Brown: Wood rats and kangaroo rats: potential reservoirs of the Lyme disease spirochete in California. Journal of Medical Entomology 28 (3), 1991, pp. 299-302, PMID 1875357 . ( Full text )
- ↑ Daniel Rejmanek, Gideon BRADBURD, Janet Foley: Molecular characterization Reveals distinct genospecies of Anaplasma phagocytophilum from various North American hosts. Journal of Medical Microbiology 61 (2), February 2012, pp. 204-212, doi : 10.1099 / jmm.0.034702-0 , PMID 1875357 . ( Full text )
- ^ A b Antoinette J. Piaggio, Greg S. Spicer: Molecular Phylogeny of the Chipmunk Genus Tamias Based on the Mitochondrial Cytochrome Oxidase Subunit II Gene. Journal of Mammalian Evolution 7 (3), September 2000, pp. 147-166, doi : 10.1023 / A: 1009484302799 . ( Full text )
- ^ A b Antoinette J. Piaggio, Greg S. Spicer: Molecular Phylogeny of the Chipmunks Inferred from Mitochondrial Cytochrome b and Cytochrome Oxidase II Gene Sequences. Molecular Phylogenetics and Evolution 20 (3), September 2001, pp. 335-350, doi : 10.1006 / mpev.2001.097 . ( Full text )
- ↑ a b c Tamias (Neotamias) sonomae . In: Don E. Wilson , DeeAnn M. Reeder (Eds.): Mammal Species of the World. A taxonomic and geographic Reference. 2 volumes. 3. Edition. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 .
- ↑ a b Joseph Grinnell : Eutamias sonomae, a new chipmunk from the inner northern coast belt of California. Contribution from the Museum of vertebrate zoology of the University of California, University of California Press, Berkeley 1915, pp. [321] -325. ( Full text )
- ^ Howard Levenson, Robert S. Hoffmann, Charles F. Nadler, Ljerka Deutsch, Scott D. Freeman: Systematics of the Holarctic Chipmunks (Tamias). Journal of Mammalogy 66 (2), May 1985, pp. 219-242, doi : 10.2307 / 1381236 .
- ↑ Bruce D. Patterson, Ryan W. Norris: Towards a uniform nomenclature for ground squirrels: the status of the Holarctic chipmunks. Mammalia 80 (3), May 2016, pp. 241-251, doi : 10.1515 / mammalia-2015-0004 .
- ^ Noah Reid, John R. Demboski, Jack Sullivan: Phylogeny Estimation of the Radiation of Western North American Chipmunks (Tamias) in the Face of Introgression Using Reproductive Protein Genes. Systematic Biology 61 (1), 2012, pp. 44-62, doi : 10.1093 / sysbio / syr094 . PMC 3243737 (free full text)
- ^ Arthur H. Howell : Diagnoses of Seven New Chipmunks of the Genus Eutamias, with a List of the American Species. Journal of Mammalogy 3, 1922, pp. 178-185. ( Full text )
literature
- Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012, ISBN 978-1-4214-0469-1 , pp. 340-341 .
- Troy L. Best : Tamias sonomae. Mammalian Species 444, 1993.
- JL Koprowski, EA Goldstein, KR Bennett, C. Pereira Mendes: Sonoma Chipmunk. In: Don E. Wilson, TE Lacher, Jr., Russell A. Mittermeier (Eds.): Handbook of the Mammals of the World: Lagomorphs and Rodents 1. (HMW, Volume 6) Lynx Edicions, Barcelona 2016, p. 789 -790, ISBN 978-84-941892-3-4 .
Web links
- Neotamias sonomae inthe IUCN Red List of Threatened Species 2015.4. Listed by: AV Linzey, NatureServe (G. Hammerson), 2008. Retrieved August 5, 2016.
- Samir Hasmukh Shah: Tamias sonomae (Sonoma chipmunk) on Animal Diversity Web, 1999, accessed May 7, 2017.
