Nelson antelope pebble
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Nelson's antelope pebble ( Ammospermophilus nelsoni ) |
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| Ammospermophilus nelsoni | ||||||||||||
| ( Merriam , 1893) |
The Nelson antelope pebble or San Joaquin antelope pebble ( Ammospermophilus nelsoni ) is a type of squirrel from the genus of the antelope pebble ( Ammospermophilus ). It is endemic to the San Joaquin Valley in southern California . The species was named after Edward William Nelson .
features
The Nelson antelope pebble reaches a head-torso length of about 23 to 27 centimeters and a tail length of 6.6 to 7.8 centimeters with a weight of about 150 grams. The back color is yellowish to brown-sand-colored and on both sides of the body there is a single light line parallel to the spine. The ventral side is colored white to cream. The tail is sand-gray on top and cream-white on the underside.
distribution
The Nelson antelope pebble is endemic to the San Joaquin Valley in southern California . The occurrence is limited to the central and western part of the valley and extends into the neighboring areas of the inner coastal mountains in the areas of the Cuyama Valley, Panoche Valley, Carrizo Plain and Elkhorn Plain. The altitude distribution ranges from 50 to around 1100 meters in the Temblor Range, although the animals are rare above 800 meters. Significant occurrences are limited to the west of Kern County in the Elk Hills and on the Carrizo and Elkhorn Plains, in the northern part the animals occur in low density in the Panoche and Kettleman Hills.
Way of life
The Nelson antelope pebble lives in flat and dry valley regions with slopes of less than 10 to 14 °. The vegetation consists of sparse grassland with isolated bushes, the soil is loamy to sandy and gravelly, which is very hard and dry.
The animals are diurnal and can be found throughout the year, they rest in periods of extreme heat and they often stay in the shade of plants and stones to cool off. Because of their coloring, they are very well adapted to the desert and although they mainly live on the ground, they are able to climb bushes. They feed primarily on green parts of plants and on plant seeds that they collect in their cheek pouches. Depending on the season, carrion and insects also represent a significant part of the food. The animals live in flat and sometimes complex burrows with multiple exits, and they usually take over the abandoned burrows of kangaroo rats . The density of the animals is usually low due to the dry habitats, but within the colonies the burial activity of the antelope pebbles and other small mammals can lead to a significant improvement in the soil. The activity radius, regardless of gender, covers an area of around 4.4 hectares. Communication takes place via short whistles that are deep compared to the calls of other antelope pizzas, which are used as alarm calls. Otherwise the animals are very quiet and only give out low calls. Locomotion takes place by walking with the tail rolled up over the back, during which the animals scurry backwards and forwards and remain motionless in the event of potential danger or disturbance by sounds.
The mating season takes place in late winter and spring. The young are born in March in the burrows after a gestation period of 26 days, with a litter consisting of six to eleven, on average 9, young. The young animals leave their maternal den in April, when the rains in spring lead to increased plant growth. The mortality is very high, and die more than 80% of the animals in the first year. The most important predators are the silver badger ( Taxidea taxus ), foxes, coyotes and birds of prey.
Systematics
The Nelson antelope pebble is classified as a separate species within the genus of the antelope pebble ( Ammospermophilus ), which consists of five species. The first scientific description as Spermophilus nelsoni comes from Clinton Hart Merriam in 1893 using individuals from the area of Tipton , Tulare County , in the San Joaquin Valley in California. In 1909 the species was transferred by Marcus Ward Lyon and Wilfred Hudson Osgood to the genus Ammospermophilus established by Merriam in 1862 . A close relationship to the Texas antelope pebble ( Ammospermophilus interpres ) should exist.
Apart from the nominate form, no further subspecies are distinguished within the species .
Status, threat and protection
The Nelson antelope pebble is classified as endangered by the International Union for Conservation of Nature and Natural Resources (IUCN). This is justified by the very small distribution area of less than 5,000 km 2 , the strong fragmentation of the habitat and the increasing deterioration in habitat conditions. The main threats to the species come from the transformation of habitats into agricultural areas and the spread of neophytes with dense vegetation. The species is not hunted and is not considered an agricultural pest.
The population size is unknown, according to estimates of three to ten animals per hectare and an area of around 41,000 hectares, a minimum population size of 124,000 to 413,000 is estimated. The species is common in the Carrizo Plain National Monument .
supporting documents
- ↑ a b c d e f g h i j k Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 254-255. ISBN 978-1-4214-0469-1
- ↑ a b c d e Ammospermophilus nelsoni in the Red List of Threatened Species of IUCN 2015-4. Listed by: JO Whitaker Jr., NatureServe (G. Hammerson, DF Williams), 2008. Retrieved May 9, 2016.
- ^ A b c Troy L. Best , Amy S. Titus, Cynthia L. Lewis, Katherine Caesar: Ammospermophilus nelsoni . In: Mammalian Species . tape 367 , 1990, pp. 1–7 ( full text (PDF)). Full text ( Memento of the original from March 4, 2016 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ a b c Ammospermophilus nelsoni In: Don E. Wilson , DeeAnn M. Reeder (Ed.): 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 .
literature
- Troy L. Best , Amy S. Titus, Cynthia L. Lewis, Katherine Caesar: Ammospermophilus nelsoni . In: Mammalian Species . tape 367 , 1990, pp. 1–7 ( full text (PDF)).
- Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012; Pp. 254-255. ISBN 978-1-4214-0469-1
Web links
- Ammospermophilus nelsoni onthe IUCN 2015-4 Red List of Threatened Species . Listed by: JO Whitaker Jr., NatureServe (G. Hammerson, DF Williams), 2008. Retrieved May 9, 2016.
- Divya Balaji: Ammospermophilus nelsoni on the University of Michigan Museum of Zoology's Animal Diversity Web. Retrieved May 9, 2016.