Richardson Collar Lemming
| Richardson Collar Lemming | ||||||||||||
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| Scientific name | ||||||||||||
| Dicrostonyx richardsoni | ||||||||||||
| Merriam , 1900 |
The Richardson collar lemming or Manitoba collar lemming ( Dicrostonyx richardsoni ) is a rodent in the burrower family that is found in central areas of Canada .
features
The species reaches a total length of 12.5 to 17.2 cm, including a 0.9 to 2.7 cm long tail and a weight of 64 to 120 g. The hind feet are 1.5 to 2.3 cm long and the length of the ears is about 0.3 cm. Like other members of the genus, the Richardson collar lemming is characterized by a torpedo-shaped body, short limbs, and small eyes and ears. In autumn the long white winter hairs begin to grow, which have a gray base that occasionally shines through. As a further adaptation to winter, larger cushions are formed on the third and fourth fingers, which are covered by a shovel-shaped claw . According to another source, the maximum total length is 14.8 cm and the weight varies between 45 and 72 g.
The shorter summer coat consists of brown hair on top with a more or less distinct red tip, which creates a speckled appearance. In addition, there is a dark line of eel that is narrower than other collar lemmings . The underside is covered by light brown fur with various reddish areas. The eponymous collar is just a red spot on the throat of many specimens, although some individuals have a closed band. The tail is dark on top, light brown on the underside and equipped with a small white tassel at the tip. There is one incisor, no canine, no premolar and three molar teeth per half of the jaw , which results in a total of 16 teeth.
distribution
The distribution area is west of Hudson Bay in the province of Manitoba as well as in the areas of Nunavut and Northwest Territories . It extends at least as far as the Great Slave Lake , although the exact western limit has not been established.
Way of life
The Richardson Collared Lemming can be found in open and dry areas of the tundra , humid and wooded regions are only populated when there is strong population pressure. They dig their burrows in various substrates, but prefer dry and stony sandy soils. They mainly use these burrows to rest and to escape potential predators. They are both diurnal and nocturnal, with activity tapering off at midnight and early in the morning. They are also active all year round. The animals feed on green vegetation, flowers, berries, buds, roots and willow bark .
Reproduction takes place throughout the year, with litters usually not occurring or only when there is strong population development, especially in autumn and winter. The males are polygynous and mate accordingly with several females. In contrast to the females, they are not territorial and their areas of activity usually overlap with those of several females and males. The gestation period is 20 to 21 days and the females give birth to between one and eight young per litter. In doing so, they usually use a burrow near the border of their action area for rearing. In one couple kept in captivity, 17 consecutive litters were observed. Father animals may take part in the rearing of the offspring, for example through grooming and protection. The young rarely leave the nest for the first five days. The eyes open by around 11 to 15 days, which leads to more exploration of the area. At 16 to 20 days, the boys are largely independent. There can be strong fluctuations in the populations within the populations , with a rhythm of 2.8 to four years between the population maxima was determined. The animals act as intermediate hosts for individual coccidia such as Sarcocystis .
Systematics
The Richardson collar lemming is recognized as an independent species within the collar lemmings (genus Dicrostonyx ) within the voles . The first scientific description was made by the American naturalist Clinton Hart Merriam in 1900, who introduced the species under the name Dicrostonyx richardsoni . Merriam she described of individuals from the region around Fort Churchill in Manitoba , Canada. It was temporarily assigned to the Northern Collared Lemming ( Dicrostonyx groenlandicus ) as a subspecies, but was later recognized as one of a total of six species in North America based on karyological data and mating studies.
Individual fossil finds from the US states of Iowa and South Dakota , which date to the maximum of the last glacial period around 20,000 years ago, were originally assigned to the real collar lemming ( Dicrostonyx torquatus ). Here, DNA studies showed that the findings are more likely to be assigned to the Richardson collar lemming. Accordingly, the species occurred further south in North America at that time. The former landscape there south of the border of the Laurentide Ice Sheet with its bush tundra was largely similar to that used by today's representatives west of Hudson Bay.
status
As with other collar lemmings, the population size fluctuates from year to year. At times, 25 specimens per hectare can be found. There are no known threats to the species. It is listed by the IUCN as not at risk (least concern) .
Individual evidence
- ↑ Don E. Wilson , DeeAnn M. Reeder (Ed.): Mammal Species of the World . A taxonomic and geographic Reference . 3. Edition. 2 volumes. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 (English, Dicrostonyx richardsoni ).
- ↑ a b Donna Naughton (Ed.): The Natural History of Canadian Mammals . University of Toronto Press, 2012, ISBN 978-1-4426-4483-0 , pp. 125 (English, Dicrostonyx richardsoni ).
- ↑ a b c d e Richardson's Collared Lemming. In: UFJ Pardiñas, D. Ruelas, J. Brito, LC Bradley, RD Bradley, N. Ordóñez Garza, B. Kryštofek, JA Cook, E. Cuéllar Soto, J. Salazar-Bravo, GI Shenbrot, EA Cjoquito, AR Percequillo , JR Prado, R. Haslauer, JL Patton, I. León-Paniagua: Family Cricetidae (True Hamsters, Voles, Lemmings and New World Rats and Mice). In: Don E. Wilson, TE Lacher, Jr., Russell A. Mittermeier (editors): Handbook of the Mammals of the World: Rodents II. (HMW, Volume 7) Lynx Edicions, Barcelona 2018, p. 298. ISBN 978 -84-16728-04-6 .
- ↑ a b c Dicrostonyx richardsoni in the endangered Red List species the IUCN 2017. Posted by: Cassola, F., 20,168th Accessed December 28, 2018th
- ↑ Anna Maria Gajda, Ronald J. Brooks: Paternal Care in Collared Lemmings (Dicrostonyx richardsoni): Artifact or Adaptation? Arctic 46 (4), 1993, pp. 312-315.
- ↑ Susan C. Quinn, Ronald J. Brooks, Richard J. Cawthor: Effects of the protozoan parasite Sarcocystis rauschorum on open-field behavior of its intermediate vertebrate host, Dicrostonyx richardsoni. Journal of Parasitology 73 (2), 1987, pp. 265-271.
- ↑ Tara L. Fulton, Ryan W. Norris, Russell W. Graham, Holmes A. Semken, Beth Shapiro: Ancient DNA supports southern survival of Richardson's collared lemming (Dicrostonyx richardsoni) during the last glacial maximum. Molecular Ecology 22, 2013, pp. 2540-2548.