Mongolian racing rat

Mongolian racing rat
Mongolian racing rats
Systematics
Family : Long-tailed mice (Muridae) Subfamily : Gerbils (Gerbillinae) Tribe : Gerbillini Sub tribus : Rhombomyina Genre : Racing rats ( meriones ) Type : Mongolian racing rat
Scientific name
Meriones unguiculatus
( Milne-Edwards , 1867)

The Mongolian racing rat ( Meriones unguiculatus ) is a type of gerbil belonging to the racing rats . It inhabits steppes, semi-deserts, deserts and grasslands in Mongolia and adjacent areas in northern China , Manchuria and southern Siberia and is not endangered. Described as Gerbillus unguiculatus by Alphonse Milne-Edwards in 1867 , its scientific species name refers to the striking, comparatively large, dark-colored claws .

It is active during the day and at night, does not hibernate and lives in family groups within colonies. Their burrow is usually five to six meters long with five to ten entrances, a nest chamber and one or two pantries. It prefers to feed on green parts of plants as well as plant seeds and builds winter supplies. The Mongolian racing rat is the most common gerbil kept as a test and pet animal and there are different colors.

"Mongolian racing rat", "Mongolian gerbil", "Mongolian gerbil", "Mongolian gerbil" and "Mongolian gerbil" are used as German trivial names . The Gerbil rat is simply " gerbil ", " gerbil " or, from the English equivalent, as " Gerbil called". The translation of the scientific name Meriones unguiculatus as "warrior with claws" is wrong, since the generic name Meriones does not refer to the mythical hero Meriones from the Iliad , but to the thighs of animals. The name is derived from the ancient Greek mēros (μηρός "thigh").

anatomy

The claws of the Mongolian racing rat are comparatively large and dark in color.

Dimensions and proportions

The Mongolian racing rat is slightly smaller than other gerbils in its range. Their head-torso length is usually 97 to 132 millimeters, the tail length 85 to 110 millimeters, the hind foot length 24 to 32 millimeters, the ear length 13 to 15 millimeters and the largest skull length 30 to 36 millimeters. At 70 to 92 percent of the length, the tail is slightly shorter than the head and torso.

The head is short and broad with slender, protruding auricles. The neck looks very short. The hind legs are long and well developed, but the hind paws are not particularly elongated. The claws of the front paws, however, are significantly enlarged and occupy a middle position between those of the Indian desert rat and those of the other racing rats.

With regard to body size, no noticeable differences between males and females could be found in nature. The average body weight of 25 adult males in Inner Mongolia was around 60 grams and that of 11 females around 59 grams, with three males and none of the females having a body weight of less than 50 grams. In captivity, however, males are on average slightly larger than females. Males usually weigh 80 to 130 grams and females 70 to 100 grams.

Fur and color

ruddy fur

The fur of the Mongolian racing rat is rather short and less soft than usual for racing rats. The undercoat is fine and woolly, the upper fur a bit firmer and longer. The hair on the top and bottom are usually around ten millimeters long.

From the snout to the tail, the fur on the upper side is grayish-brown, reddish-brown-yellow or ocher-brown-yellow. It is pale brownish yellow on the sides of the body. The individual hairs are ocher-brown-yellow, slate-gray at the base, some with black tips. In between there are some longer, completely black hairs on the back, which lead to an overall slightly darker color.

An indistinct, light brown to brownish-yellowish-white ring runs around the eyes. This color extends backwards over the cheeks to the base of the auricles. Short hairs of the same color cover the front outside of the auricles and longer, whitish hairs cover the back outside. The edges are lined with short, also whitish hair. Apart from a few very short, whitish to brownish-yellow hairs near the tip of the ear, the inside of the auricle is almost hairless. The eyes are black and the 5 to 40 millimeter long whiskers are mixed black and white in color.

The lower lip, chin, upper part of the throat and the inside of the front legs are pure white to the base of the hair. There is sometimes a pale, brownish-yellow color in the upper center of the chest. The rest of the underside is white or light brown and the hairs have a gray base unlike other racing rats in their area of ​​distribution. The transition between the fur on the sides of the body and that of the underside is grayish and blurred.

The hair of the tail is less than 10 millimeters long at the root and up to 20 millimeters long at the tip. The back half has a comb of longer hair on top and a pronounced, black tassel at the top. The tail is described as ocher-colored all around or clearly two-colored, dark gray on the top and pale brown on the underside. In contrast to the midday rat, there are short, black hairs on the back of the tail.

The soles of the hind paws are completely covered with sandy-gray hair, with the exception of a hairless patch on the heel. Their upper side is colored pale brown-yellow. In contrast to the Libyan racing rat and Meriones chengi , the hind paws have no hairless area near the ankle. In contrast to those of the midday rat, the claws are grayish black or dark brown.

Skull and teeth

Skull of a Mongolian racing rat (without lower jaw and with damaged zygomatic arches)

The skull of the Mongolian racing rat is similar to that of the midday racing rat, but the facial skull is higher and the zygomatic arches are more widely spread. With a length of up to 36 millimeters, it is shorter than the skull of the Afghanistan racing rat and, unlike this, the zygomatic arch plate at the rear end is clearly separated from the body of the zygomatic arches. Their greatest width usually exceeds the common width of the upper incisors measured on the tooth sockets. The bone ridges above the eye sockets are weak and protrude slightly. The nasal bones are narrow and slightly shorter than the nasal process of the intermaxillary bones . The intermediate parietal bone is mainly oval in shape and the posterior border is arched backwards, but the anterior border where it touches the parietal bones forms more of a triangle with a point towards the front.

The tympanic bladders are inflated at the back and large with a length of about 31 percent of the length of the skull, although smaller and less inflated at the front than in the midday rat. They do not extend to the anterior outer surface of the auditory canals, but their size leads to a narrowing of the basioccipital of the occiput and to their anterior ends approaching each other up to a distance of 1.5 millimeters. The external auditory canals do not reach the zygomatic arches, but unlike the Afghanistan racing rat, their lower wall is clearly swollen. The addition eardrum is greater than the Azeri race rat and smaller than in the Afghanistan racing rat, the lunch and the race rat race Libyan rat.

Characteristic of the lower jaw are the comparatively broad ascending branches, the short muscle and articular processes and the long angular process. The attachment points of the masticatory muscles are thus well developed. The greatest skull length of five specimens from Shaanxi and Mongolia was 33.9 to 35.8 millimeters, the basal length 29.2 to 30.5 millimeters, the palatal length 17.5 to 18.8 millimeters, the zygomatic width 18.2 to 19.6 millimeters, the mastoid width 18.5 to 19.6 millimeters, the width over the molars 6.8 to 7.0 millimeters, the length of the upper molar row 4.3 to 5.0 millimeters and the length of the lower molar row 4 .6 to 4.8 millimeters.

1	·	0	·	0	·	3	=  16
1	·	0	·	0	·	3

Mongolian racing rat tooth formula

The bite has one than that of all racing rats in each half of the jaw incisor tooth trained incisor and three hochkronige , non-renewable molars on. A change of teeth does not take place. The longitudinal furrow of the upper incisors is pronounced and lies slightly to the side of the center. The first molar tooth has three tooth strips that are separated from one another by two indentations on the inside and outside, the second molar tooth has two strips and the third molar tooth is small with an almost circular crown.

Body skeleton

The spine of the Mongolian racing rat consists of seven cervical, twelve thoracic, seven lumbar, four cross and 20 to 24 caudal vertebrae. The atlas and axis of the cervical spine are very well developed, while the other five cervical vertebrae, with their very short, smooth bodies, are weaker. The atlas has strong, rearward-directed processes and a distinct, pointed ventral tubercle on the abdomen . The spinous process is very pronounced on the axis . The length of the transverse processes of the cervical vertebrae increases backwards.

The rib cage is large, wide open at the back and is bordered at the bottom by seven sternal and five asternal ribs , the last two of which are flesh ribs . The front of the sternum has only a thin edge of cartilage and forms two wide, V-shaped bone plates for the movable connection with the clavicles and the first pair of ribs. Its body is made up of four star braces. The collarbone is fully developed, about ten millimeters long, and the shoulder blade has a particularly pronounced shoulder bone that ends in the bone corner.

The hip bone hole of the pelvis is comparatively wide. The fibula is slender, lies slightly to the side behind the shin and both bones fuse together in the lower half. Of the tarsal bones is the heel bone well trained. The first toe of the front paws is rudimentary, the other four toes and the five toes of the rear paws are normal. The second to fifth toes are made up of three links each.

organs

The protruding eyes of the Mongolian racing rat are on the sides of the head. Your retina is rich in rods with a cone content of only 14 to 20 percent and the iris is dark. The males' brains weigh about 1.02 grams and the females about 1.18 grams. The olfactory bulb is very well developed and a Jacobson organ is present. Thirty-eight pairs of nerves branch off  from the spinal cord : eight from the cervical cord , 13 from the thoracic cord , seven from the lumbar cord , three from the cruciate cord , and seven from the caudal cord .

The windpipe runs to the left of the esophagus. Some cartilage braces are C-shaped and not completely closed on the back. The lungs weigh about 400 milligrams and the right lung has four lobes and the left three lobes. About 40 percent of the animals have an incomplete arterial ring in the brain . The heart weighs about 420 milligrams. The thymus remains in adult animals and is divided into two lobes, which lie completely or, in young animals, about two-thirds in the thorax. The spleen weighs about 130 milligrams and is located in the left costal region.

The thyroid is bilobed, yellowish and lies on the side and middle of the larynx. The parathyroid glands lie slightly to the side in front of the anterior thyroid poles. The adrenal glands lie in the middle of the anterior kidney pole and their mass is comparatively high compared to body weight. The ratio between its mass and body weight is three to four times that of the rat. The left adrenal gland weighs about 30 milligrams, the right about 25 milligrams. The pancreas consists of the body, a right wing and a left wing and weighs around 220 milligrams. The liver consists of a left, a right and a middle section and weighs about 4.6 grams. The gallbladder is bean-shaped.

The stomach is composed of a single cavity, formed as a blind sac, and a large forestomach division and a small gastric glandular division, and in males it can be almost completely shifted into the chest. The duodenum consists of the initial part, the descending and the ascending part, the empty intestine has an average of seven garland-like loops and the ileum is very short. The appendix is large and hook-shaped, is divided into the head, body and tip, and in males it can be shifted to the chest. The colon is divided into ascending, transverse and descending colon and the rectum is almost twice as long in males as in females. The total length of the intestine is about 54.5 centimeters.

The kidneys are bean-shaped, blackish-smooth and dark brown-red. They are about 13 millimeters long and 8 millimeters wide, the left kidney weighs about 370 milligrams, the right one 360 ​​milligrams. Except for the abdominal surface, they are surrounded by ample brown fat tissue . The renal papillae are very long and the length ratio of the papillae and the renal medulla to the renal cortex is twice that of the rat . The Henle's loops are extremely long. The ureters run parallel to the posterior vena cava and open into the urinary bladder at the back . This is filled spherical, measures seven to eight millimeters in diameter, also protrudes slightly filled into the abdominal cavity and is underlaid by a large V-shaped fat pad. In females, the urethra runs on the abdomen side of the uterus, cervix and vagina and opens independently on a conical protrusion on the abdomen side of the vulva. In the male, it is divided into a pelvic section about ten millimeters long and a penis section.

The testicles of the males are egg-shaped, about 13 millimeters long, 9.5 millimeters thick and weigh about 575 milligrams. They lie completely in the process of the vagina , which is completely encompassed by the testicular lifter muscle . The functional tissue is very soft and a body of connective tissue is not visible. The epididymis consist of the strong head, the thin body as a connecting piece and the tail, are grayish-yellowish and weigh about 1330 milligrams including the adjacent fat pads. White fatty tissue surrounds the anterior testicle pole and parts of the epididymis, extends into the abdominal cavity and in sexually mature males leads to considerable forward changes in the position of the gastrointestinal tract. The spermatic duct is about a millimeter thick, surrounded by a thick, grayish-white layer of fat and there are outer and inner ampoule glands. The seminal bladder gland is formed in pairs, the prostate consists of an anterior, a posterior and a strongly articulated middle lobe, and the urethral gland is also formed in pairs. The penis has a noticeable kink with a rearward end section and its total length is about 22 millimeters. It is of the fibroelastic type and consists of two penile and one urethral erectile tissue . A five to six millimeter long penis bone is embedded in the rear end section of the urethra . A small extension protrudes over the urethra as a tip cap by about one millimeter. The penile foreskin is about eight millimeters long and protrudes two to three millimeters beyond the penis. There are no or two foreskin glands . The distance between the opening of the foreskin and the anus is about twelve millimeters in adult males.

The ovaries of the females are located in the fifth to sixth lumbar vertebrae, the left ovary is a little further back. They are about the size of a grain of rice and bean-shaped, weigh about eight to nine milligrams and are about four to five millimeters long. The fallopian tubes are very tortuous and about 18 millimeters long. The uterus consists of two horns lying in front and the body lying behind. The horns are measured 16 to 18 millimeters long with a slightly shorter left horn in adult females. The two horns run side by side separately and open into an unpaired section of the cervix . The rear part of the uterus appears uniform on the outside and the length from the bifurcation to the vagina is about five millimeters. The external cervix is bounded by four folds of the mucous membrane and the vagina is about 15 millimeters long. The distance between the vulva and anus is about five millimeters in adult females.

The skin is darkly pigmented, the tail skin is loose and the skin has no sweat glands . The mammary gland tissue of females can expand over both shoulders and far back into the perineum area. It has four glandular complexes, each with a pair of teats : one in the chest, one in the chest-stomach, one in the abdomen and one in the groin. Behind the eyeball, the nictitating membrane has a Harder's gland , the ducts of which open in front of and below the nictitating membrane. In the middle of the abdomen there is a collection of 200 to 300 holocrine , enlarged sebum glands connected to hair follicles . This abdominal gland is about 5 by 25 millimeters in males and about 4 by 15 millimeters in females.

Large fat pads occur in the connective tissue of the subcutaneous tissue , as a covering for the organs and sometimes also between the muscles . They consist of brown and white adipose tissue and are more pronounced in males than in females.

Body function

The breathing rate of the Mongolian racing rat is 70 to 120 and an average of 90 puffs per minute, the heart rate is 260 to 430 and an average of 360 beats per minute and the body temperature is around 36 to 39 and an average of 38 degrees Celsius. With regard to the ambient temperature , it is adapted to a wide range. The indifference temperature is between 30 and 35 degrees Celsius. At temperatures above it appears to be seriously affected.

Senses

The sight of the Mongolian race rat is adapted to their flight behavior. The sight of the eyes is almost 360 degrees and the visual fields overlap only slightly, so that stereoscopic vision is hardly possible. Since there are only a few cones, color perception is limited, while the numerous rods enable good night vision .

The sense of hearing is designed for sound with frequencies between 0.1 and 60 kilohertz, in particular between 0.2 and 32 kilohertz. With a peak between three and five kilohertz, like other desert-dwelling rodents, it is adapted to lower frequencies than mice and rats . The very good hearing ability in the range between one and four kilohertz is probably used for the perception of predators, as no sounds are emitted in this area . In contrast, these are mainly concentrated between four and six kilohertz and around ten kilohertz and around 15 kilohertz.

The sense of smell is very well developed and the olfactory cells of the olfactory mucous membrane are numerous. The vibrissae on the muzzle, above the eyes, on the outside of the body and legs, and pressure receptors on the paws are responsible for the sense of touch and orientation .

Food and hydrogen switch

In a food intake of five to seven grams per day, the Mongolian race rat 1.5 sets to 2.5 grams of feces from. The fecal balls are formed in the first U-loop of the ascending part of the colon. In addition, appendix containing vitamin B is excreted. A bulge in the mucous membrane at the transition from the stomach to the esophagus makes vomiting impossible.

When water is freely available, it consumes about 0.039 milliliters per gram of body weight per day. It can use salt water with a concentration of 0.8 mol of salt per liter of water. Without freely available water, it survives well and stabilizes after a loss of around 14 percent of body weight. Compared to rats, hamsters and guinea pigs , the average blood plasma volume only decreases slightly. With a water intake of four to seven milliliters per day, she secretes three to four milliliters of urine . The appendix is ​​probably of particular importance for regulating the water balance.

blood

The blood volume of the Mongolian racing rat averages 7.76 milliliters per 100 grams of body weight and the blood plasma volume averages 5.27 milliliters per 100 grams of body weight. In adult animals, the hematocrit value is 43 to 51 percent and the amount of hemoglobin is 10.7 to 16.5 grams per deciliter. The number of red blood cells is seven to ten million per microliter, that of white blood cells is 3,200 to 12,200 per microliter and that of platelets is 400,000 to 600,000 per microliter. The differential blood count shows 1.3 to 5.2 percent or 3,000 to 4,100 neutrophils per microliter, 0.07 to 0.32 percent or up to 4,000 eosinophils per microliter, 0.1 to 0.28 percent or up to 2,000 basophils per microliter , 0.03 to 0.25 percent or up to 9,000 monocytes per microliter and 5.1 to 11.8 percent or 32,000 to 97,000 lymphocytes per microliter. The proportion of reticulocytes is 2.0 to 5.4 percent.

The half-life of red blood cells is short, around ten days. Therefore, there is an increased formation of reticulocytes and polychromatism . Especially up to the 20th week of life there is a high number of red blood cells with a basophilic grain , which occurs in immature red blood cells as a residue of cytoplasmic ribonucleic acid . Males have higher hematocrit and hemoglobin levels than females, as well as higher total white blood cells and higher numbers of lymphocytes circulating in the blood.

4.3 to 12.5 grams of plasma proteins are dissolved per deciliter of blood plasma , of which 1.2 to 6.0 grams are globulins and 1.8 to 5.5 grams are albumin . The concentration of glucose is 50 to 135 milligrams per deciliter, that of urea 17 to 32 milligrams, of creatinine 0.64 to 1.12 milligrams, of cholesterol 90 to 151 milligrams, of bilirubin 1.3 to 2.5 milligrams and of Uric acid 1.1 to 2.8 milligrams per deciliter. The amount of sodium is 143 to 165 millimoles per liter, that of potassium with 3.9 to 9.3 millimoles per liter, of calcium with 2 to 2.5 millimoles per liter or with 3.6 to 6.0 milligrams per deciliter , of chlorides with about 105 millimoles per liter and of phosphorus with 3.7 to 7.1 milligrams per deciliter.

The plasma proteins, including the glycoproteins, change with the age of the animals. Blood cholesterol levels rise quickly and for a long time after ingestion of cholesterol, and even a diet with a fat content of only four to six percent leads to high blood cholesterol levels , especially in adult males .

Glands

For the metabolism of cholesterol, its conversion into steroid hormones is more important in the Mongolian racing rat than in the rat. The wide metabolic range of the adrenal gland is also very different from that of the rat. It is rich in lipids , but unlike most mammals, it produces only small amounts of corticosterone .

When the lid closes , the Harder's gland releases secretions consisting of protoporphyrins , fatty acids and pheromones . This leads to a red coloration of the tears due to the porphyrin , is transported via the tear-nasal duct to the nostrils and distributed over the body together with the saliva when cleaning. The secretion enables the body temperature to be regulated . It insulates against cold and moisture and increases light absorption by darkening . If the body temperature is to be lowered, the secretion decreases and the proportion of saliva increases, which leads to cooling through evaporation.

The secretion from the abdominal gland is yellow, musky and consists mainly of phenylacetic acid . The hair protruding from the glands, furrowed and directed backwards enables the optimal placement of the secretion on objects. The development of the abdominal gland is androgen dependent and it becomes active with the onset of sexual maturity. It is particularly well developed in dominant males, it is also active in other males and dominant females, and it is small and inactive only in subordinate females with delayed sexual maturity. Females have an enlarged abdominal gland during pregnancy and milk delivery . Castration leads to regression , but the administration of testosterone reverses this process. In males and females with existing sex glands, the gland can be stimulated by serum gonadotropin from pregnant females and responds to progesterone and testosterone in females before sexual maturity .

genetics

Karyotype
2n = 44	NF = 78

The double set of chromosomes in the Mongolian racing rat has 44 chromosomes . 22 autosomes are metacentric, 10 submetacentric and 10 acrocentric. The X chromosome is large and submetacentric, the Y chromosome smaller and also submetacentric. The number of chromosome arms is thus 78. With regard to the nuclear chromatin of the cells of several organs, there is a sexual dimorphism .

Habitat and way of life

habitat

The Mongolian racing rat often lives in the same habitat as the Brandt steppe vole and their burrows.

The habitat of the Mongolian racing rat are steppes , semi-deserts , deserts and grasslands . It is common in areas with clay soils , on arable land and on dams , but not at all in mountainous terrain. Their preferred habitat are semi-deserts with cereal - brine - pea bush communities as well as dunes overgrown with saltpetre . However, it can easily adapt to rocky habitats and relatively humid areas overgrown with the iris iris tenuifolia and wolfberry . From south to north it increasingly prefers light, dry soils and human settlement areas . This is how it can best be observed in the northern part of its range. In eastern Mongolia, 36 percent of the rodents found on homesteads are Mongolian racing rats.

In the north and northeast of China it inhabits sandy deserts . In Inner Mongolia it is found in desert steppes and a variety of other habitats. It prefers the steppes used as pasture land and for growing potatoes with sandy soils and sparse, interrupted vegetation of grass , herbs and bushes . The climate is continental and semi-arid with cold and dry winters and hot summers. The annual rainfall of around 300 milliliters falls mainly from June to August as rain and from October to April as snow , which can remain for 20 days at a time. The monthly mean temperature in January is around minus 20 degrees and in July around plus 21 degrees Celsius, whereby temperatures of minus 40 degrees and plus 50 degrees Celsius can be reached. Strong winds are common in spring. In summer, the vegetation can at times mainly consist of Sievers mugwort .

In the south of Mongolia, the Mongolian racing rat does not particularly prefer sandy soils and occurs on more solid soils. In the north-east of Mongolia it can be found in the cereal steppes and on small sand hills covered with pea bushes, as well as on salt soils and in salt marshes that are overgrown with brine. They are usually most numerous on rubbish heaps on the edge of kitchen gardens . In the Altai-Gobi it lives in semi-deserts overgrown with grain, brine and wolfberry and is common in the gorges . In the Trans-Altai-Gobi it can be found in the oases and in the dunes overgrown with the saltpeter herb Nitraria sibirica . However, it is most numerous in the valleys of the rivers, near farmland and human settlements, and also in rubbish heaps. It was observed in the flat, barren steppe south of the Tannu-ola Mountains . In the northwest of Mongolia it avoids the sandy sickle dunes , but is quite numerous in the flat brine plains.

In Tuva she lives mainly on farmland, on the deposits of sediments of the higher wormwood -Cereals steppes and in the desert steppes and on the small-leaved pea shrub vegetation, older deposits of the lower altitudes. In the region around Lake Baikal it is absent in mixed grassland steppes , in rocky and swampy areas. It occurs there near human settlements and more frequently in wormwood steppes, in salt areas as well as on arable and pasture land . In addition, it inhabits dry sand steppes , which are overgrown with small-leaved pea bushes and white wormwood , and can be found in steppes with light, loamy soils and diverse, mixed grain-grass vegetation. There it occurs on arable land with buckwheat , millet and wheat cultivation and is quite numerous on the artificial embankments of railways , roads with and without surface layers and irrigation systems . She digs burrows in rubbish heaps as well as earthworks and avoids untouched soil.

Population density

The population density of the Mongolian racing rat varies greatly from year to year, depending on soil conditions, rainfall and snow cover, and can be exceptionally high under some conditions. An indication of the density in an area is given by the number of burrows and their entrances.

At Xilin Hot in eastern Inner Mongolia , for example, a ratio of around 5: 1 was found between entrances and animals. On fallow land near potato fields, 460 to 470 entrances were counted in June 1984 with a density of around 90 animals per hectare, on potato fields 356 to 390 entrances per hectare, on other fallow land 240 entrances per hectare, on pasture land 236 entrances per hectare and on mixed shrubbery -, fallow and arable land 214 to 252 entrances per hectare. The density probably increased in the course of the summer. In contrast, in the Siziwang banner in the center of Inner Mongolia, it was only around 30 animals per hectare in peak years.

In the flat brine plains in northwestern Mongolia 50 inhabited dwellings per hectare were found and in the Mongolian grain-pea bush desert in May 1944 an average number of 42 entrances per hectare, in dune areas an average number of 504 entrances per hectare as well in the culverts along roads a number of 2800 entrances per hectare. In Daurien, 740 to 1420 entrances per hectare were counted in similar culverts and 2500 entrances per hectare on sediment deposits, whereas in pristine soils only 30 to 32 entrances per hectare. Other counts in Daurien came to 32 burrows with 760 entrances per hectare with a temporarily lower average density. In the Baikal region, six animals per hectare were counted in the wormwood steppes, up to 15 animals per hectare in salt areas and up to 90 animals per hectare on arable and pasture land. For Tuva, between 70 and 176 animals per hectare have been reported, but this may be exaggerated.

Food and supplies

The Mongolian racing rat is a herbivore and its diet is determined by the seeds and greens of many plants . In summer it prefers green parts of plants, especially from hemp , goose feet , buckwheat , log and the shrub Atraphaxis scoparia , in winter seeds and fruits . The composition of the food varies from region to region.

In the steppes in the east of Inner Mongolia, which are mainly overgrown with mugwort, it feeds on its stems and leaves as well as Artemisia commutata , mound saltwort , green millet and leymus chinensis . Presumably it also feeds on seedlings and roots . On the arable land of Dauriens and Tuwas mainly the seeds of field crops are consumed. On fallow land, the diet includes cereals , wormwood, as well as various goosefoot family , daisy family and legumes . Oats are preferred as food over wheat . In the south-east of Dauria the main food is the Mannaklee Alhagi kirghisorum and the bug seed Corispermum duriuscula , which grow in areas abandoned by the Brandt steppe vole . With the beginning of the seasonal change in the plant cover, it begins to feed on wild grain without being able to meet its needs.

The seeds of various plants are used as winter stock . So the seeds of buckwheat, wheat, millet , oats, millet , goose feet, pea bushes and the branches of wormwood were found in the storerooms of their burrows . The amount of seeds was up to 20.5 kilograms for buckwheat and up to 1.4 kilograms for pea bushes. In the south of Dauria, the stocks consist partly of the sprouts of wormwood and salt marsh, as well as the hairy love grass . In Inner Mongolia, their storerooms contained the ears of Leymus chinensis . The pantries, which are filled from September to March, are empty from April to August. They usually contain only one type of food. This is entered from mid-August to mid-autumn and sometimes into winter, in which all animals participate. For example, adult animals can often be seen looking for food together with their offspring. While no difference could be determined with regard to age and sex when entering, there are sometimes considerable differences in individual animals.

Competitors and predators

The Daurian Pika is one of the food competitors of the Mongolian racing rat .

The food competitors of the Mongolian racing rat include the Daurian ground squirrel , the Daurian piper and the Daurian dwarf hamster . In the east of Inner Mongolia, their habitat is used as grazing land for sheep , cattle and horses .

A major predator is the eagle owl , in whose vaults the remains of the Mongolian racing rat were found. Steppe ilts and weasels were observed to disappear into the gerbil's burrows. Their activity decreased significantly when mouse weasels were present for several days. Other possible predators are the Altai weasel , the red fox , the wolf , shepherd dogs and the highland buzzard .

Age structure, gender distribution and life expectancy

Of the 126 animals caught in eastern Inner Mongolia in June 1984, 19 percent were juveniles , 54 percent adolescents and 27 percent adults . Four percent were probably at least eight or nine months old, meaning they were born in the autumn of the previous year at the latest. Of the young animals, 42 percent were male, of the teenagers 58 percent and of the reproductive animals 68 percent. Nine of the eleven adult females captured were either pregnant or suckling and at least eleven adolescent females and 29 adolescent males were imminent to reproductive capacity.

The average life expectancy of the Mongolian racing rat in nature is probably no more than three to four months. A tagged adult female was caught a second time in almost a year, after spending her second winter. For example, the maximum life expectancy in nature is around two years or a little longer, and within a year a population is usually completely renewed. In captivity, however, life expectancy is usually three to four years.

construction

The building of the Mongolian racing rat serves as protection from extreme temperatures, rain and snow, strong winds and from predators.

Created in dry sand or clay , it differs depending on the type of landscape. It is relatively simple or complex, usually five to six meters and up to 14 meters long. Most of the five to ten entrances open horizontally or diagonally to the earth's surface. A nest chamber and one or two storage chambers are located in the central part of the system. The nest chamber is usually at a depth of 40 to 45 centimeters in summer construction and at a depth of 110 to 150 centimeters in winter construction. At 45 to 60 centimeters, the passages, which are usually not very deep, measure around four centimeters in diameter. The round nest is usually six to four inches long and eight to eight inches wide. It consists of the leaves and sprouts of buckwheat and millet , otherwise of sweet and sour grasses , as well as hair and feathers and sometimes waste.

Temporary structures are located within 10 to 20 meters of the actual structure. These are no longer than two to four meters and have one to three entrances. Sometimes they contain small chambers in which leftover food can be found. The Mongolian racing rat often uses the burrows of the Brandt steppe vole.

Activity, sociality and mobility

The Mongolian racing rat is diurnal and nocturnal , but mainly diurnal in winter and does not sleep either winter or summer . It prefers early morning and early evening, but is active on the earth's surface even at temperatures above 38 degrees Celsius in summer and below 0 degrees in winter. During the hot season it is not active at noon, in spring and autumn it is also inactive on cold nights and in winter it only appears on the surface of the earth on warm days. When the weather is cold and windy, she doesn't leave the burrow and feed on her supplies. It is most active during the breeding season and when registering supplies.

It lives in colonies , preferably in family groups that defend their burrows together. In the south-east of Dauria, one to three adult males, two to seven adult females and a total of 3 to 14 animals were caught in a burrow in the summer. Family groups consisting of parents and their last litter also spend the winter in the same building. Like the gerbil , however, it does not live exclusively in small family groups, but in somewhat larger groups that can consist of several adult males and females, adolescents and young animals of different generations . Animals seek out neighboring burrows, which are sometimes connected to one another. Stranger conspecifics are chased away, but compared to other gerbils it is sociable and extremely tolerant of conspecifics. In November their whistles can often be heard, which are similar to those of the Daurian whistling hare , but a little quieter and more melodic. In spring, however, it is rather quiet. The animals signal danger to each other by drumming their hind paws.

In summer, the Mongolian racing rat covers distances of 1.2 to 1.8 kilometers every day. Their movements are not targeted and never exceed the limits of their action space, which extends over 700 meters . It is very mobile and the stocks of different burrows mix very strongly in summer and autumn. Investigations of marked animals in the southeast of Dauria revealed fluctuations of 10 to 32 percent in the population of adult males, of 18 to 52 percent in adult females and of 22 to 28 percent in young animals. Between March and August, the proportion of animals caught for the first time in each den was between 72 and 89 percent. Over a period of 120 days, one to six animals could be caught in 43 percent of the burrows, 7 to 16 animals in 44 percent of the burrows and 17 to 22 animals in 13 percent of the burrows. Most of the animals were caught in the largest burrows or in those along the hiking trails. For an adult female, the longest use of the same burrow was from May to August, for an adult male from March to June, and for a young female, 3.5 months. If the food supply deteriorates significantly, migration can occur. Distances between 15 and 20 kilometers, occasionally up to 40 kilometers along roads and in one case of 50 kilometers are known.

Reproduction and development

Mongolian racing rats are still naked and blind two days after birth.

The reproduction of the Mongolian racing rat mainly takes place in February to September. In tests in Daurien , 90 percent of the females were pregnant in February , in March it was 13 to 27 percent, in April to May 38 to 50 percent, in June 30 to 33 percent, in July 0 percent and in August to September 0 to 33 percent. The females gave birth to up to three litters per year and the young of the first litter began to reproduce in the same year. Due to a shorter breeding period, there are only two litters per year in Mongolia, and occasionally a third litter in September. The pairing usually takes place at night. The male taps his hind legs while courting and mates with the female several times. After a gestation period of 29 to 30 days, two to eleven young animals are born; the average is 6.4. The gestation period in captivity, on the other hand, is usually given as 24 to 26 days, but also as 19 to 21 days. During this time, the female gains weight by 10 to 30 grams. The litter size in captivity is one to twelve, usually four to six and an average of five young. There are contradicting data on the gender distribution at birth: the distribution should either be balanced or the male animals should predominate. The young are born during the day or at night and the mother usually consumes the afterbirth and any stillbirths . Both the male and the female take part in building nests and caring for the young.

The females of the Mongolian racing rat go through many sexual cycles per year, the length of which is four to six days; it's four days on average. Vaginal swabs reveal three phases of the cycle. The heat lasts for 12 to 18 hours and leads to spontaneous ovulation . The females are in heat again immediately after birth. Previously virgin, sexually mature females release an average of 5.4 egg cells within five days of mating  ; when you first ovulate after giving birth, there is an average of 5.6 egg cells. Eight to twelve hours after copulation and about four hours after ovulation, the sperm enter the egg cells. They have a finely tapered tip and appear to lose their head cap upon penetration . The first cleavage of the egg cells is completed 22 to 24 hours later, the second is estimated to be more than 30 hours after the first, and further cleavage occurs at intervals of 20 to 24 hours. Six days after mating and 102 hours after ovulation, the egg cells are mainly found in the uterus as blastocysts with more than 30 cells . Egg implantation may be delayed if more than two young animals are suckled. There are also indications of the possibility of a false pregnancy of 13 to 23 days. While the females' ability to reproduce ultimately ends, ovulation and mating can still occur after the birth of the last litter.

As a nestling , the Mongolian racing rat is born naked and pink with closed eyes and ears. The birth weight is 3 grams, on the tenth day the young animals weigh 7 grams, after one month 23 grams, after two months 40 to 41 grams, after three months 46 grams and after five months 48 to 60 grams. Animals born in spring reach a body weight of 60 to 70 grams and a body length of 110 to 120 millimeters by autumn. Animals born in summer reach similar proportions by spring. The young animals are suckled up to an age of 20 to 25 days . The birth weight in captivity is given as 2.5 grams. From 2 to 5 days after birth, the ear cups unfold that the first hairs develop on the 6th or 7th day, the breakthrough of the incisors takes place between the 10th and the 16th day and the eyes open between the 16th and 20th day. The young animals start to eat solid food from the 16th day, but they are suckled in captivity up to an age of 20 to 30 days and a body weight of 12 to 18 grams. Then they can feed themselves on seeds. The testicle descent occurs between the 28th and 45th day and the vagina opens between the 40th and 76th day. Females become sexually mature after 65 to 85 days , males after 70 to 85 days. In captivity, females usually reproduce between 7 and 20 months of age, with males beyond 24 months of age.

Distribution and existence

distribution

The distribution area of the Mongolian racing rat is Mongolia and neighboring areas in northern China , Manchuria and southern Siberia . In Mongolia, it comes in the Great Lakes sink , the Valley of the Lakes , the southern Khangai Mountains , along the rivers of the north-eastern Khangai Mountains Orkhon and Selenge , in the middle Chalcha , the North Gobi and eastern Mongolia ago .

In China it is widespread in the center and north of Inner Mongolia as well as from east Gansu via north Ningxia , Shaanxi and Shanxi to Hebei and Liaoning . To the east it occurs to Manjur and Hailar in Inner Mongolia and Tongyu and Changchun in Jilin , south to Chifeng and Hohhot in Inner Mongolia and to the Ordos Plateau northwest of Jingbian in Shaanxi. Finds from the Hami Mountains and the Bogda Mountains have been reported, but their occurrence in Xinjiang is controversial.

It was not known from the steppes of Dauria until 1939, but in the 1940s two populations emerged on the lower reaches of the Orkhon and the Unda, separated by more than 300 kilometers from their main distribution area . It probably reached this northern limit by being introduced. Via Kjachta and Jida in Buryatia and Borsja in the Transbaikalia region, it spread further north, east and west across the Yenisei and as far as Tuva . It reaches the south of Tuva via the Great Depression in Mongolia. In the west and east of the Tannu-ola Mountains , it occurs up to an altitude of 2100 meters above sea level.

Fossil finds

Fossil finds of the Mongolian racing rat are known from the Old Pleistocene of Dauria.

Duration

The World Conservation Union IUCN classified the Mongolian racing rat in 2008 as not endangered (least concern) . This is justified with their population size and wide distribution. A population decline could not be determined, it is a common species and occurs in numerous protected areas . In Mongolia, for example, around six percent of its range is in protected areas. Although it as a pest fights and hallway fires and possibly habitat destruction by grazing increasing numbers of livestock being affected, no significant, large-scale hazards are known. However, further studies of population size and evolution are recommended.

Systematics and nomenclature

External system

Within the racing rats, Ellerman and Morrison-Scott (1951), Musser and Carleton (1993), Pawlinow (2003) and Musser and Carleton (2005) assign the Mongolian racing rat as one of several species of the Pallasiomys subgenus . Pawlinow and Rossolimo (1987) list them as the only species of the Meriones unguiculatus group within this subgenus . Ellerman (1941) does not recognize Pallasiomys and assigns the group to the subgenus Meriones . According to molecular genetic studies of mitochondrial cytochrome - b - and 12S rRNA genes, the Mongolian race rat is close to the noon race rat as with the Libyan race rat , the King racing rat and Sundevall racing rat related.

Internal system

1 2 3 4th 5 A. B. B.

Type localities of the Mongolian racing rat: Gerbillus unguiculatus Milne-Edwards, 1867 Gerbillus kozlovi Satunin, 1903 Meriones kurauchii Mori, 1930 Meriones kurauchii chihfengensis Mori, 1939 Pallasiomys unguiculatus selenginus Heptner, 1949 Locations of the captured specimens: A. Animals caught in 1935 B. Animals caught in 1995

Pawlinow et al. (1990) did not examine a subdivision of the Mongolian racing rat into subspecies . Denys (2017) does not distinguish between subspecies, but considers the species to be monotypical . Gulotta (1971), on the other hand, recognizes four subspecies:

• Meriones unguiculatus unguiculatus (Milne-Edwards, 1867) with the synonym chihfengensis Mori, 1939 in Mongolia and in China except Manchuria,
• Meriones unguiculatus kozlovi (Satunin, 1903) [also written koslovi ] in western Mongolia and Tuwa ,
• Meriones unguiculatus kurauchii Mori, 1930 in Manchuria and
• Meriones unguiculatus selenginus (Heptner, 1949) in southern Dauria .

Corbet (1978) only differentiates between the nominate form Meriones unguiculatus unguiculatus and Meriones unguiculatus selenginus . He assigns the names chihfengensis , koslovi and kurauchii as synonyms of the nominate form. Gromow and Jerbajewa (1995), on the other hand, also name Meriones unguiculatus koslovi in Tuwa as another possible subspecies. The coat color of the Mongolian racing rat becomes lighter towards the south, the length of the tail increases and the darkest and most short-tailed form is Meriones unguiculatus selenginus in Dauria. According to Smith and Hoffmann (2008), only the nominate form occurs in China.

Ellerman (1941) still lists Meriones kozlovi as an independent species in the Meriones libycus group. He lists Meriones kurauchii as an unspecified, independent species. Allen (1940) assigns kozlovi and chihfengensis as synonyms to Meriones unguiculatus . The underside of kozlovi was described as clearer white without the yellowish color that sometimes occurs in unguiculatus , but the difference does not seem to justify recognition as an independent subspecies. This feature as well as the almost oval parietal bone are presumably subject to strong scattering. Chaworth- Musters and Ellerman (1947) assign koslovi , kurauchii and chihfengensis also to Meriones unguiculatus . Ellerman and Morrison-Scott (1951) consider koslovi and chihfengensis to be synonyms of Meriones unguiculatus unguiculatus , but provisionally recognize Meriones unguiculatus kurauchii as another subspecies because they were unable to see any specimens from Manchuria.

nomenclature

Armand David acquired several specimens of the Mongolian racing rat on his research trip to Mongolia in 1866.

Alphonse Milne-Edwards described this as Gerbillus unguiculatus in 1867 .

On the morning of April 14, 1866, Armand David acquired three specimens of a hitherto unknown "yellow rat" with a long, hairy tail on his research trip to Mongolia. The specimens sent to the Muséum d'Histoire Naturelle in Paris were first described in 1867 by Alphonse Milne-Edwards as Gerbillus unguiculatus . Milne-Edwards did not specify a type specimen . Using the travel diary published by David, Chaworth-Pattern and Ellermann (1947) delimited the type location on Ershisanhao ("Eul-che-san-hao") about ten kilometers northeast of Zhanggao ("Tschang-Kur") in Inner Mongolia (previously in northern Shanxi). Milne-Edwards emphasized the black and strong claws of the Mongolian racing rat compared to the midday racing rat. The species name unguiculatus ('with little claw') is derived from the Latin unguicula , a diminutive of unguis ('nail, claw').

During a three-year research trip through Central Asia, Pyotr Kuzmich Koslow collected further specimens of the Mongolian racing rat in the Altai in western Mongolia: a female in August 1899 on the lower reaches of the Khovd Gol at an altitude of 4100 feet, a male and a female in September 1899 on the southern slope of the Altai and three males and three females on September 28 at "Chaljumgol" at an altitude of 4200 feet. Konstantin Alexejewitsch Satunin described the specimens in the Zoological Museum of the Imperial Academy of Sciences in Saint Petersburg in 1903 as Gerbillus kozlovi . Chaworth-Musters and Ellerman (1947) limited the type locality of this form to the lower reaches of the Chowd Gol.

Tamezō Mori collected an adult male in October in Shuangliao ("Cheng-chia-tun") in central Manchuria and described this in 1930 as Meriones kurauchii . Another adult male collected on October 6, 1933 in Chifeng in eastern Inner Mongolia, he described in 1939 as Meriones kurauchii chihfengensis . Finally, in 1949, Vladimir Georgievich Geptner described a form in the Zoological Museum of Moscow University from the Selenga Mountains near Kjachta in southern Buryatia as Pallasiomys unguiculatus selenginus .

Oldfield Thomas used the combination Meriones unguiculatus for the first time in 1908 , Geptner used the combination Pallasiomys unguiculatus for the first time in 1933 .

Mongolian racing rat and human

Pest and disease vector

The Mongolian racing rat is considered a pest in grain cultivation and is a natural host for pathogens causing zoonoses such as the plague , swine rot , alveolar echinococcosis and possibly schistosomiasis . However, it is largely free from endemics and parasitoses .

History and scope of the attitude

The Mongolian racing rat of various colors exist in captivity .

In 1935 T. Kasuga caught 20 pairs of the Mongolian racing rat in the Amur Basin in eastern Mongolia and sent them to the Kitasato Institute in Tokyo to examine rickettsiae . From this inventory, Mitchi Nomura built another colony in Tokyo's central laboratory for laboratory animals in 1949 . In 1954 she sent eleven pairs to the Tumblebrook Farm founded by Victor Schwentker in Brant Lake, New York, for the production of laboratory animals , where four males and five females were able to breed. Shortly thereafter, the first specimens were taken into pet ownership. In Europe, keeping them as an experimental animal began in the 1960s. In 1964, J. H. Marston introduced twelve Massachusetts couples to the UK and established a colony at the University of Birmingham . Further specimens were caught in central Mongolia in 1995 and 60 of these were successfully bred.

The Mongolian racing rat is the most common gerbil kept as a test and pet animal . For example, about 100,000 specimens are used in research in the United States each year, and in 1996 more than 760,000 specimens were kept in nearly 280,000 households. It is also kept as a feed animal . There are different colors .

Use in research

The Mongolian racing rat is used in basic research , medical , physiological and psychological research. It is used extensively in research into aging , hearing , dental diseases , hormones , cancer , nutrition , the effects of radiation , reproduction , infectious diseases and strokes . Further examinations concern the urinary and sexual apparatus , the peripheral and the central nervous system .

It is suitable as a model organism for researching the human hearing, because the curve of the hearing sensitivity is very similar to that of humans up to a frequency of ten kilohertz and because it is very robust with regard to otitis media. In dentistry, it is a suitable model because of its susceptibility to periodontitis and dental caries . It is also well suited for investigations into the development of skin melanomas . In cancer and transplant research, it has proven to be comparatively resistant to X-rays .

An important area of ​​application is parasitological research. It was used as a model host for the bacteria Bordetella bronchiseptica , Yersinia enterocolitica , Bacillus anthracis , Listeria monocytogenes , Staphylococcus aureus , piliforme Clostridium , Mycoplasma , leprae Mycobacterium , Mycobacterium tuberculosis , Mycobacterium bovis and Leptospira used. It is also susceptible to the unicellular organisms Leishmania , Toxoplasma and Babesia , the tapeworm Echinococcus , filariae and other roundworms such as Ascaris , Dipetalonema , Nematospiroides and Trichostrongylus as well as the great liver fluke . It is also highly susceptible to viral infections of the respiratory tract as well as all viruses of the poliovirus and Coxsackie groups and therefore a suitable model for the development of vaccines .

The Mongolian racing rat is used in many pharmacological experiments. Compared to hamsters and mice, the late prenatal development is slower, so that an exact timing of the administration of medication and the recovery of the embryos are possible. The effect of were examined prochlorperazine on the metabolism of the tranquillizers reserpine and chlorpromazine , which increase the homovanillic acid triggered concentration in the brain of Triethyltin , silver nitrate , pentylenetetrazol , Flurothyl and cobalt to brain damage, the response of the ileum to nicotine and acetylcholine and the blocking effect of atropine , morphine and adrenaline . In behavioral studies , the effect of was alcohol , amphetamines , barbiturates and cannabinoids observed and toxicological studies of carcinogens , pesticides and heavy metals . The artificial sweetener cyclamate, for example, causes chromosomal damage in bone marrow cells and chronic lead poisoning causes histopathological and haematological changes similar to those in humans.

Their specialized sebum glands are ideal for acne research and their unique lipid metabolism makes them a suitable model for cholesterol research . A diet with a cholesterol content of over 0.2 percent leads to an accumulation of cholesterol in the liver and thus to fatty liver disease , cirrhosis and impaired liver function. Despite lipemia , there is no arteriosclerosis .

Neurological examinations concern, among other things, spontaneously occurring and induced cramps and the blood circulation of the brain. It is suitable as a model for local anemia in the human brain and thus in stroke research. In animals with an incomplete ring of arteries, a one-sided constriction of the common carotid artery on the same side leads to a cerebral infarction .

Housing conditions

With regard to its keeping , the Mongolian racing rat is not the easy-care and undemanding species that it is often described as in the literature. In experimental animal husbandry, the lack of irritation in the standard cages and the lack of opportunities to retreat do not meet their needs at all. As a pet, the owner's ignorance, their complex way of life and climatic environmental factors such as excessively high humidity stand in the way of animal-friendly keeping . Housing facilities currently in use are based more on experience than on scientifically proven knowledge.

The optimal temperature is between 19 and 24 degrees Celsius. Values ​​below 15 and above 29 degrees Celsius can be problematic for newborn, old and sick animals. However, fluctuations within this range are tolerated without any problems. If it is possible to create an insulating nest in deep litter, temperatures between 0 and 35 degrees Celsius can also be tolerated when the humidity is low and there is unlimited availability of food. The optimal relative humidity is between 30 and 50 percent and thus lower than in other rodents kept as experimental animals. Values ​​over 50 percent limit the thermoregulation, especially in connection with high temperatures . Keeping them in a damp living area or basement is therefore seen as problematic. The European Commission (2007) recommends a relative humidity of 35 to 55 percent for animal husbandry. In addition to year-round keeping at room temperature, keeping and wintering in escape-proof outdoor terrariums that protect against predators is also possible in Central Europe, if the creation of a corridor system with a nest in a frost-free area is possible and food and water are always available.

The required air exchange rate depends on the occupancy density, the type of housing and other factors. Drafts also impair the thermoregulation, a draft of air with a speed of up to 0.25 meters per second is tolerated . The Mongolian racing rat can adapt to a day length of 12 to 14 hours with an illuminance of up to 60 lux. Interruptions in the light phases can lead to changes in behavior and body function. Permanent light or permanent darkness are to be avoided. Both vibrations and A- weighted sound pressure levels above 50 decibels lead to considerable stress. Above all, unknown, suddenly occurring noises including ultrasound sounds disrupt well-being and can be harmful to health.

A suitable enclosure takes into account the Mongolian racing rat's need for movement and exploration through its size, structure and three-dimensional room design. Cage types III and IV are mostly used in experimental animal husbandry (820 and 1,800 cm² base area; 18 and 20 cm² height). The dimensions given for the pet industry vary widely, but the dimensions are not the biggest concern. The TVT (2014) specifies a lower shell for two animals with a base area of ​​0.5 square meters and a height of 50 centimeters plus a 30 centimeter high attachment. For each additional animal, the area increases by 0.125 square meters. In a survey of 136 owners, 37 percent did not meet these criteria and a further 43 percent only partially.

The amount of basic feed to be offered is around ten grams per animal and day. Fatty food is preferred and in excess can lead to obesity. Juice feed serves to supply water, but can not replace the constant availability of free drinking water .

Conspecifics are particularly important due to the sociable way of life of the Mongolian racing rat. Behavioral patterns required for later life are learned and damage is avoided if the separation from the parent animals only takes place after experience in caring for the subsequent litter has been gained. In pairs and groups, however, it can lead to aggressive disputes and even damage fights. In laboratory animal husbandry, the mating of a male with a female is more successful than the mating of a male with two to three females. In experiments that require individual housing, males seem to be more suitable than females.

Overall, there is still a need for research on the little-known needs of the Mongolian racing rat and their behavior. Schulze Sievert (2002) brings together the knowledge about various forms of husbandry and discusses ways to scientifically proven animal-friendly husbandry. Waiblinger (2010) as well as Batchelder and colleagues (2012) are dedicated to keeping them as laboratory animals.

Captive refugees

The keeping of pets of the Mongolian racing rat poses significant risks to the environment, agriculture and human health. Every year there are hundreds to thousands of prisoner refugees who can spread quite widely. It is feared that the species could establish itself as a neozoon in some areas of North America and elsewhere.

Several short-lived colonies of wild Mongolian racing rats are known from England . As a prisoner refugee, she quickly established herself under the floors of houses and outbuildings and can survive in less protected environments. The best-documented colony originated in 1973 on the Isle of Wight . So were at Cothey Butts near Fishbourne the BBC TV series after finishing Tales of the Riverbank next pet rats , hamsters and guinea pigs and rats exposed Mongolian race. While the other species quickly disappeared, their population grew by a group of houses and a barn, in a wood store and on fallow land to over 100 animals by February 1976. However, the extent of human support through additional feeding or releasing more animals during this time is unknown. Several colonies of the Mongolian racing rat are also known from Yorkshire . In 1971, presumably abandoned pets were discovered in the moors near Thorne and Goole, far from human settlements . In Armthorpe, near Doncaster, from 1972 to 1973, animals living under sheds were found that had escaped from a school laboratory. In 1975 more animals escaped and the colony still existed in 1977. In 1975, three animals were discovered in a burrow near Bradford that was built under tree roots in a wooded area near a large housing estate. In March 1987 skeletal remains of the species were found in a fresh vault of a long-eared owl at its roost in the Denaby Ings Nature Reserve near Mexborough . A melanistic animal was discovered in a flower shop in Bolton, near Manchester, in 1996 . It was possibly imported in a shipment of cut flowers from the Netherlands, where such animals were common. Further finds come from Harrogate (1977) and Doncaster (1980/1981). Although the Mongolian racing rat reproduced wildly, the populations described, limited in time and space, cannot be regarded as established. They all disappeared without specific control measures. There is no information on the damage caused.

In North America, it is feared that established populations of the Mongolian racing rat may damage crops and embankments, and even displace native rodents. For example, Fisler (1968) examined under laboratory conditions their potential dominance in one-to-one encounters with 15 Southern California rodent species in the desert and the chaparral . It dominated nine other species, was about level with four species and had to be subordinate to two species. The dominated were the silk pocket mouse Perognathus longimembris , the wire-haired pocket mouse Chaetodipus californicus , the kangaroo rats Dipodomys merriami and Dipodomys agilis as well as the deer mouse Peromyscus crinitus , Peromyscus eremicus , Peromyscus maniculatus , Peromyscus boylcusii and Peromyscus boylcusii . The encounters with the kangaroo rat Dipodomys deserti , the grasshopper mouse Onychomys torridus and the bush rats Neotoma lepida and Neotoma fuscipes were undecided . The Mongolian reindeer rat was mostly inferior to the white-tailed antelope and round-tailed ground squirrel. If given enough time, however, it could also dominate the last six species.

In California import, transport and possession are prohibited live gerbils. For scientific purposes, however, an exception was made that requires its own approval. Gerbils imported in private vehicles are killed at the control stations that have existed since 1921 if they are not transported out of the state by their owners. However, Mongolian racing rats were found during regular inspections of pet shops. In Hawaii , the Mongolian racing rat is only allowed to be imported by government institutions for research. Their importation into New Zealand is also prohibited .

Web links

Commons : Meriones unguiculatus  - collection of images, videos and audio files

Wikibooks: The gerbil  - learning and teaching materials

• Meriones unguiculatus onthe IUCN Red List of Threatened Species .
• Information on Rennmaus.de

literature

• Greta Ågren, Zhou Qing-Qiang, Zhong Wen-Qin (1989a): Ecology and social behavior of Mongolian gerbils, Meriones unguiculatus , at Xilinhot, Inner Mongolia, China. In: Animal Behavior. Vol. 37, No. 1, pp. 11-27. doi : 10.1016 / 0003-3472 (89) 90002-X
• Greta Ågren, Zhou Qing-Qiang, Zhong Wen-Qin (1989b): Territoriality, cooperation and resource priority: Hoarding in the Mongolian gerbil, Meriones unguiculatus . In: Animal Behavior. Vol. 37, No. 1, pp. 28-32. doi : 10.1016 / 0003-3472 (89) 90003-1
• Glover Morrill Allen (1940): The Mammals of China and Mongolia. Part 2. In: Walter Granger (Ed.): Natural History of Central Asia, Vol. 11. American Museum of Natural History, New York, pp. 621-1350.
• Simon J. Baker (1990): Escaped exotic mammals in Britain. In: Mammal Review. Vol. 20, No. 2-3, pp. 75-96. doi : 10.1111 / j.1365-2907.1990.tb00105.x
• Margaret Batchelder, Lynn S. Keller, Mary Ball Sauer, Wanda L. West (2012): Gerbils. In: Mark A. Suckow, Karla A. Stevens, Ronald P. Wilson (Eds.): The Laboratory Rabbit, Guinea Pig, Hamster, and Other Rodents. Academic Press (Elsevier), Amsterdam et al., ISBN 978-0-12-380920-9 , pp. 1131-1155.
• Batsaichan Njamsuren, Jekaterina Alexandrowna Zyzulina (2008): Meriones unguiculatus . In: IUCN (Ed.): IUCN Red List of Threatened Species. Version 2009.1.
• Susan A. Brown, Karen L. Rosenthal (Eds., 2002): Kleinsäuger. Veterinary revision course. Eugen Ulmer, Stuttgart-Hohenheim, ISBN 3-8252-2264-0 (Original title: Self-Assessment Color Review of Small Mammals. Translated by Ulrike Falkenstein-Recht, first edition: 1997).
• James Lawrence Chaworth-Patterns, John Reeves Ellerman (1947): A revision of the genus Meriones . In: Journal of Zoology. Vol. 117, No. 2-3, pp. 478-504. doi : 10.1111 / j.1365-2907.1990.tb00105.x
• Chevret Pascale, Gauthier Dobigny (2005): Systematics and evolution of the subfamily Gerbillinae (Mammalia, Rodentia, Muridae). In: Molecular Phylogenetics and Evolution. Vol. 35, No. 3, pp. 674-688. doi : 10.1016 / j.ympev.2005.01.001
• Gordon Barclay Corbet (1978): The Mammals of the Palaearctic Region. A Taxonomic Review. British Museum (Natural History) / Cornell University Press, London / Ithaca, ISBN 0-8014-1171-8 (improved reprint from 1980).
• Armand David (1867): Journal d'un voyage en Mongolie fait en 1866. Bulletin des Nouvelles archives du Muséum d'Histoire naturelle. Vol. 3, pp. 18-96.
• Christiane Denys, Peter J. Taylor, Ken P. Aflin (2017): Family Muridae (true mice and rats, gerbils and relatives). In: Don E. Wilson, Thomas E. Lacher jr., Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. 7. Rodents II. Lynx Edicions, Barcelona, ISBN 978-84-16728-04-6 , pp. 536-884.
• John F. Eisenberg (1975): The behavior patterns of desert rodents. In: Ishwar Prakash, Pulak K. Ghosh (Eds.): Rodents in Desert Environments. Dr. W. Junk bv, The Hague, ISBN 90-6193-080-4 , pp. 189-224.
• John Reeves Ellerman (1941): The Families and Genera of Living Rodents. Volume II. Family Muridae. British Museum (Natural History), London.
• John Reeves Ellerman, Terence Charles Stuart Morrison-Scott (1951): Checklist of Palaearctic and Indian Mammals 1758 to 1946. British Museum (Natural History), London.
• Anja Ewringmann, Barbara Glöckner (2008): Key symptoms in hamsters, rats, mice and gerbils. Enke, Stuttgart, ISBN 978-3-8304-1063-8 .
• Karl J. Field, Amber L. Sibold (1999): The Laboratory Hamster & Gerbil. CRC Press, Boca Raton et al., ISBN 0-8493-2566-8 .
• George F. Fisler (1977): Potential behavioral dominance by the Mongolian gerbil. In: The American Midland Naturalist. Vol. 97, No. 1, pp. 33-41. doi : 10.2307 / 2424682
• Ursula Friederich, Werner Volland (1998): Feed animal breeding. 3rd edition, Eugen Ulmer, Stuttgart-Hohenheim, ISBN 3-8001-7382-4 .
• Elina Grodtmann (2007): Abdominal sonography of the Mongolian gerbil ( Meriones unguiculatus Milne-Edwards 1867). Dissertation, Munich.
• Igor Michailowitsch Gromow, Margarita Alexandrovna Yerbajewa (1995): Млекопитающие фауны России и сопредельных территорий (зайsыгdы Russia) of Territories (The зайsыгdыобразные размистаразные) ростали и сопредельных территорий (зайsыгdы Russia бразные) Russian Academy of Sciences (Zoological Institute), Saint Petersburg.
• Elizabeth Fryatt Gulotta (1971): Meriones unguiculatus . Mammalian species. No. 3, pp. 1-5.
• Joachim Haensel (1983): 100 Tips for Small Mammals Friends [= Berlin Zoo Book, No. 34]. Urania, Leipzig / Jena / Berlin.
• Daphne M. Hills (1991): Ephemeral introductions and escapes. In: Gordon Barclay Corbet, Stephen Harris (Eds.): The Handbook of British Mammals. 3rd edition, Blackwell Scientific Publications, Oxford et al., ISBN 0-632-01691-4 , pp. 576-580.
• Johann Karl Wilhelm Illiger (1811): Prodromus systematis mammalium et avium additis terminis zoographicis utriusque classis, eorumque versione Germanica. C. Salfeld, Berlin.
• Ewald Isenbügel (1985): Small mammals. In: Edwald Isenbügel, Werner Frank (Hrsg.): Heimtierkrankheiten. Eugen Ulmer, Stuttgart-Hohenheim, ISBN 3-8001-2533-1 , pp. 13-160.
• Yukibumi Kaneko, Kishio Maeda (2002): 日本人 の 研究者 に よ る 哺乳類 の 学名 学名 と 模式 標本 の リ ス 卜. [A list of scientific names and the types of mammals published by Japanese researchers]. 哺乳類 科学 [Honyurui Kagaku = Mammalian Science]. Vol. 42, No. 1, pp. 1-21. doi : 10.11238 / mammalianscience.42.1
• Michael O. Keffer (1974): The detection of exotic vertebrate pests in California. Proceedings of the 6th Vertebrate Pest Conference (1974). No. 25, pp. 227-230.
• Douglas M. Lay (1972): The anatomy, physiology, functional significance and evolution of specialized hearing organs of gerbilline rodents. In: Journal of Morphology. Vol. 138, No. 1, pp. 41-120. doi : 10.1002 / jmor.1051380103
• Christopher Lever (1977): Naturalized Animals of the British Isles. Hutchinson, London, ISBN 0-09-127790-6 .
• Christopher Lever (1985): Naturalized Mammals of the World. Longman, London / New York, ISBN 0-582-46056-5 .
• Christopher Lever (2009): The Naturalized Animals of Britain and Ireland: Mammals, Birds, Reptiles, Amphibians and Fish. New Holland, London / Cape Town / Sydney / Auckland, ISBN 978-1-84773-454-9 .
• John L. Long (2003): Introduced Mammals of the World: Their History, Distribution and Influence. CSIRO Publishing / CABI Publishing, Collingwood / Wallingford, ISBN 0-643-06714-0 .
• Alphonse Milne-Edwards (1867): Observations sur quelques mammiferes du nord de la Chine. Annales des sciences naturelles. Row 5, Vol. 7, pp. 374-377.
• Guy G. Musser, Michael D. Carleton (1993): Family Muridae. In: Don E. Wilson, DeeAnn M. Reeder (Eds.): Mammal Species of the World . A Taxonomic and Geographic Reference. 2nd edition, Smithsonian Institution Press, Washington, ISBN 1-56098-217-9 , pp. 501-755.
• Guy G. Musser, Michael D. Carleton (2005): Superfamily Muroidea. In: Don E. Wilson, DeeAnn M. Reeder (Eds.): Mammal Species of the World . A Taxonomic and Geographic Reference. 3rd edition, Johns Hopkins University Press, Baltimore, ISBN 0-8018-8221-4 , pp. 894-1531.
• Nikolai Pawlowitsch Naumow, WS Lobachev (1975): Ecology of desert rodents of the USSR (jerboas and gerbils). In: Ishwar Prakash, Pulak K. Ghosh (Eds.): Rodents in Desert Environments. Dr. W. Junk bv, The Hague, ISBN 90-6193-080-4 , pp. 465-598.
• Jochen Niethammer (1988): Wühler. In: Bernhard Grzimek (Ed.): Grzimek's Enzyklopädie Säugetiere. Volume 5. pp. 206-265 (eleven-volume licensed edition of the original edition from 1988).
• Ronald M. Nowak (1999): Walker's Mammals of the World . 6th edition, Johns Hopkins University Press, Baltimore / London, ISBN 0-8018-5789-9 .
• Igor Jakowlewitsch Pavlinow (2003): Систематика современных млекопитающих Систематика современных млекопитающих. Moscow State University, Moscow.
• Igor Jakowlewitsch Pavlinow, Ju. A. Dubrowski, Olga Leonidowna Rossolimo, Je. G. Potapowa (1990): Песчанки мировой фауны [Gerbils of the World]. Nauka, Moscow, ISBN 5-02-005350-3 .
• Igor Jakowlewitsch Pawlinow, Olga Leonidowna Rossolimo (1987): Систематика млекопитающих СССР. Moscow State University, Moscow.
• Fred Petrij, Karin van Veen, Michael Mettler, Vera Brückmann (2001): A second acromelanistic allelomorph at the albino locus of the Mongolian gerbil ( Meriones unguiculatus ). Journal of Heredity. Vol. 92, No. 1, pp. 74-78.
• Rudolf Piechocki (1969): Family Wühler. In: Irenäus Eibl-Eibesfeldt, Martin Eisentraut, Hans-Albrecht Freye, Bernhard Grzimek, Heini Hediger, Dietrich Heinemann, Helmut Hemmer, Adriaan Kortlandt, Hans Krieg, Erna Mohr, Rudolf Piechocki, Urs Rahm, Everard J. Slijper, Erich Thenius ( Ed.): Grzimeks animal life . Encyclopedia of the Animal Kingdom. Eleventh volume. Mammals 2. Kindler, Zurich, pp. 301–344.
• Konstantin Alexejewitsch Satunin (1903): New Rodents from Central Asia. Ежегодникъ 3оологическаго Музея Императорской Академiи Наукъ. Vol. 7 [1902], pp. 547-589.
• Günter Schmidt (1985): Hamsters, guinea pigs, mice and other rodents. 2nd edition, Eugen Ulmer, Stuttgart-Hohenheim, ISBN 3-8001-7147-3 .
• Ute Elisabeth Schulze Sievert (2002): A contribution to the animal-friendly keeping of the Mongolian gerbil based on literature. Dissertation, Hanover.
• Andrew T. Smith, Robert S. Hoffmann (2008): Subfamily Gerbillinae. In: Andrew T. Smith, Xie Yan (Eds.): A Guide to the Mammals of China. Princeton University Press, Princeton / Oxford, ISBN 978-0-691-09984-2 , pp. 247-252.
• Veterinary Association for Animal Welfare (2014): Mongolian gerbils. Pp. 1-3.
• Eva Waiblinger (2010): The laboratory gerbil. In: Robert Hubrecht, James Kirkwood (Eds.): The UFAW Handbook on the Care and Management of Laboratory and Other Research Animals. 8th Edition, Wiley-Blackwell, Chichester / Ames (Iowa), ISBN 978-1-4051-7523-4 , pp. 327-347.
• Jürgen Weiß, Jürgen Maeß, Klaus Nebendahl, Walter Rossbach (eds., 1996): Domestic and laboratory animal care. Gustav Fischer, Stuttgart / Jena / New York, ISBN 3-437-20524-2 .
• Peernel Zwart, Annemariereiber (2008): Gerbil. In: Karl Gabrisch, Michael Fehr, Lutz Sassenburg, Peernel Zwart (ed.): Diseases of pets. 7th edition, Schlütersche Verlagsgesellschaft, Hanover, ISBN 978-3-89993-038-2 , pp. 161-182.

Remarks

1. ^ Niethammer, 1988 (p. 256)
2. ↑ Piechocki, 1969 (p. 343)
3. ↑ Schmidt, 1985 (pp. 149–150)
4. ↑ Weiss and co-workers, 1996 (p. 64)
5. ↑ Schulze Sievert, 2002
6. ↑ Brown and Rosenthal, 2002 (back blurb)
7. ↑ Ewringmann and Glöckner, 2008 (pp. 6–9)
8. ↑ ^{a b} Isenbügel, 1985 ("Biologie der Wildform", pp. 81–82)
9. ↑ Illiger, 1811 ( p. 82 )
10. ↑ ^{a b c d e f g h} Smith and Hoffmann, 2008 (p. 251)
11. ↑ ^{a b c d e} Gulotta, 1971 ("General Characters" p. 1)
12. ↑ ^{a b c d e f} Gromow and Jerbajewa, 1995 ( Memento from March 22, 2007 in the Internet Archive )
13. ↑ ^{a b c d e f g h i j} Allen, 1940 ("Description", pp. 783–784 )
14. ↑ ^{a b c d e f g h} Isenbügel, 1985 ("Anatomie" pp. 82–85)
15. ↑ ^{a b} Ellerman, 1941 ( p. 528 )
16. ↑ ^{a b} Allen, 1940 ("Measurements" p. 784 )
17. ↑ ^{a b} Ågren and co-workers, 1989a (p. 15)
18. ↑ Agren et al, 1989a (13)
19. ↑ ^{a b c} Zwart and Driver, 2008 ("Physiologische Daten" p. 164 )
20. ↑ ^{a b c} Ellerman, 1941 ( p. 531 )
21. ↑ ^{a b c d e f g h i} Schulze Sievert, 2002 (p. 177)
22. ↑ ^{a b c d e f} Gulotta, 1971 ("Form" p. 2)
23. ↑ ^{a b c d} Gulotta, 1971 ("Diagnosis" p. 1).
24. ↑ ^{a b c} Gromow and Jerbajewa, 1995 ( Meriones ( Memento from March 22, 2007 in the Internet Archive ))
25. ↑ Smith and Hoffmann, 2008 ("Key" p. 249)
26. ^ Lay, 1972 (p. 51)
27. ↑ ^{a b c d e} Schulze Sievert, 2002 (p. 172)
28. ↑ ^{a b c d} Schulze Sievert, 2002 (p. 176)
29. ↑ ^{a b c d} Schulze Sievert, 2002 (p. 45)
30. ↑ ^{a b c d} Schulze Sievert, 2002 (p. 173)
31. ↑ ^{a b} Schulze Sievert, 2002 (p. 174)
32. ↑ ^{a b} Field and Sibold, 1999 ( p. 9 )
33. ↑ Schulze Sievert, 2002 (p. 175)
34. ↑ ^{a b c d e f} Zwart and Driver, 2008 ("Anatomical and physiological features" pp. 163–164 )
35. ↑ Grodtmann, 2007 (p. 7)
36. ↑ ^{a b c d e} Schulze Sievert, 2002 (p. 46)
37. ↑ ^{a b c d e f g} Gulotta, 1971 ("Function" p. 2)
38. ↑ ^{a b} Gulotta, 1971 ("Behavior" p. 3)
39. ↑ Lay, 1972 (pp. 82-83)
40. ↑ Schulze Sievert, 2002 (Tab. 3, p. 75)
41. ↑ ^{a b c d e} Isenbügel, 1985 ("Physiologie" pp. 85–86)
42. ↑ Isenbügel, 1985 ("Fütterung" p. 87)
43. ↑ Field and Sibold, 1999 (Tab. 1, p. 10 )
44. ↑ ^{a b c} Schulze Sievert, 2002 (pp. 180–181)
45. ↑ ^{a b} Field and Sibold, 1999 (Tab. 4, p. 11 )
46. ↑ ^{a b} Field and Sibold, 1999 (Tab. 2, p. 10 )
47. ↑ ^{a b} Schulze Sievert, 2002 (p. 66)
48. ↑ Schulze Sievert, 2002 (p. 71)
49. ↑ Gulotta, 1971 ("Genetics" p. 3)
50. ↑ ^{a b c d e f g h} Batsaichan and Zyzulina, 2008
51. ↑ ^{a b c d e f} Naumow and Lobatschew, 1975 (p. 531)
52. ↑ ^{a b c} Naumow and Lobachev, 1975 (p. 530)
53. ↑ ^{a b c} Ågren and co-workers, 1989a (p. 11)
54. ↑ Agren et al, 1989a (p.12)
55. ↑ ^{a b c d e f} Ågren and co-workers, 1989a (p. 14)
56. ↑ ^{a b c d e f g} Naumow and Lobatschew, 1975 (p. 535)
57. ↑ Ågren and co-workers, 1989a (Table 1, p. 15)
58. ↑ ^{a b} Ågren and co-workers, 1989a (p. 22)
59. ↑ ^{a b c d e} Naumow and Lobatschew, 1975 (p. 532)
60. ↑ ^{a b c d e f g h} Gulotta, 1971 ("Ecology" p. 3)
61. ↑ Ågren and co-workers, 1989b (p. 28)
62. ↑ Agren et al, 1989a (23)
63. ↑ Naumow and Lobachev, 1975 (p. 533)
64. ↑ Eisenberg, 1975 (p. 211)
65. ↑ ^{a b c d e f g h} Naumow and Lobatschew, 1975 (p. 534)
66. ^ Eisenberg, 1975 (p. 216)
67. ↑ Naumow and Lobachev, 1975 (p. 536)
68. ↑ ^{a b c} Field and Sibold, 1999 ( pp. 46–47 )
69. ↑ ^{a b c d e f g h i j k l} Gulotta, 1971 ("Ontogeny and Reproduction" pp. 2–3)
70. ↑ ^{a b c d e f} Field and Sibold, 1999 (Tab. 8, p. 43 )
71. ↑ ^{a b c d} Musser and Carleton, 2005 (p. 1239)
72. ↑ Gulotta, 1971 ("Distribution" p. 1)
73. ↑ ^{a b} Gromow and Jerbajewa, 1995 ( Memento of March 22, 2007 in the Internet Archive ) (distribution)
74. ^ Ellerman and Morrison-Scott, 1951 ( p. 641 )
75. ↑ Musser and Carleton, 1993 (p. 558)
76. ^ Pavlinov, 2003
77. ↑ ^{a b c} Pawlinow and Rossolimo, 1987
78. ↑ Ellerman, 1941 ( p. 536 )
79. ↑ Chevret and Dobigny, 2005 (Fig. 3, p. 682)
80. ↑ Pavlinow and colleagues, 1990 (p. 299)
81. ↑ Christiane Denys in: Denys and employees, 2017 (p. 648)
82. ↑ ^{a b c d e f} Gulotta, 1971 (p. 1)
83. ↑ ^{a b c d} Chaworth-Musters and Ellerman, 1947 (p. 483)
84. ↑ ^{a b} Gromow and Jerbajewa, 1995 (p. 371)
85. ↑ ^{a b} Corbet, 1978 (p. 126)
86. ↑ Ellerman, 1941 ( p. 535 )
87. ^ Ellerman, 1941 ( p. 537 )
88. ↑ Allen, 1940 ( p. 785 )
89. ^ Ellerman and Morrison-Scott, 1951 ( p. 641 )
90. ↑ David, 1867 ( p. 77 )
91. ↑ ^{a b} Allen, 1940 ( p. 783 )
92. ↑ ^{a b} Milne-Edwards, 1867 ( p. 377 )
93. ↑ David, 1867 ( p. 74 )
94. ↑ Satunin, 1903 ( p. 547 )
95. ↑ Satunin, 1903 ( p. 553 )
96. ↑ Kaneko and Maeda, 2002 (p. 13)
97. ↑ Kaneko and Maeda, 2002 (p. 15)
98. ↑ ^{a b c} Gulotta, 1971 (p. 3)
99. ↑ Gromow and Jerbajewa, 1995 ( Memento of March 22, 2007 in the Internet Archive ) (way of life)
100. ↑ Isenbügel, 1985 ("Diseases" p. 91)
101. ↑ Petrij and coworkers, 2001 (p. 74)
102. ↑ ^{a b} Schulze Sievert, 2002 (pp. 41–42)
103. ^ Eddie Cope: History of the Mongolian Gerbil. In: eGerbil. Retrieved September 1, 2009 . 
104. ↑ ^{a b} Schulze Sievert, 2002 (p. 86)
105. ↑ Schulze Sievert, 2002 (p. 94)
106. ↑ Friederich and Volland, 1998 (p. 156)
107. ↑ Schulze Sievert, 2002 (pp. 43–44)
108. ↑ ^{a b} Nowak, 1999 (p. 1456)
109. ↑ ^{a b c d e f g} Schulze Sievert, 2002 (p. 87)
110. ↑ ^{a b c} Schulze Sievert, 2002 (p. 88)
111. ↑ ^{a b} Schulze Sievert, 2002 (p. 164)
112. ↑ Schulze Sievert, 2002 (p. 163)
113. ↑ ^{a b} Schulze Sievert, 2002 (p. 167)
114. ↑ ^{a b c} Schulze Sievert, 2002 (p. 153)
115. ↑ ^{a b} Waiblinger, 2010 (p. 332)
116. ↑ ^{a b} Haensel, 1983 (p. 89)
117. ↑ Recommendation of the Commission of June 18, 2007 with guidelines for the housing and care of animals that are used for experiments and other scientific purposes (announced under file number K (2007) 2525) (text with EEA relevance) . (Species-specific guidelines for rodents, point 2.3).
118. ↑ Zwart and Driver, 2008 ( p. 165 )
119. ↑ Schulze Sievert, 2002 (p. 154)
120. ↑ ^{a b} Schulze Sievert, 2002 (p. 155)
121. ↑ Schulze Sievert, 2002 (p. 156)
122. ↑ ^{a b} Schulze Sievert, 2002 (p. 159)
123. ↑ Schulze Sievert, 2002 (p. 90)
124. ↑ Veterinary Association for Animal Welfare, 2014 (p. 1)
125. ↑ Keeping exotic animals and wild animals in private hands: situation analysis, assessment and need for action, particularly under animal welfare aspects. 2nd interim report.  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. (Fig. III-42, p. 130)  
126. ↑ Schulze Sievert, 2002 (Tab. 12, p. 158)
127. ↑ Schulze Sievert, 2002 (p. 157)
128. ↑ ^{a b} Schulze Sievert, 2002 (p. 161)
129. ↑ Schulze Sievert, 2002 (p. 162)
130. ↑ Schulze Sievert, 2002 (p. 59)
131. ↑ Schulze Sievert, 2002 (p. 11)
132. ↑ ^{a b c d} Baker, 1990 (p. 77)
133. ↑ ^{a b} Lever, 1977 (p. 61)
134. ↑ Lever, 2009 (p. 371)
135. ↑ ^{a b c d e} Hills, 1991 (p. 577)
136. ↑ ^{a b} Lever, 1985 (p. 372)
137. ↑ Lever, 2009 (p. 372)
138. ^ Long, 2003 (p. 160)
139. ↑ ^{a b} Fisler, 1968 (p. 33)
140. ↑ Fisler, 1968 (Tab. 1, p. 36)
141. ^ California Natural Resources Agency. Department of Fish and Game (2017): Restricted Species Laws and Regulations. Importation, Transportation and Possession of Wild Animals - Manual 671 (p. 8).
142. ^ Animal Care Panel (1968): Laboratory Animal Care. Vol. 18, Williams & Wilkins (p. 235).
143. ↑ Keffer, 1974 (p. 229)
144. ↑ Keffer, 1974 (p. 230)
145. ^ State of Hawaii. Department of Agriculture (2006): List of Prohibited Animals (p. 44).
146. ^ Hazardous Substances and New Organisms Amendment Act 2003 (p. 44).