Pygmy hippopotamus population that freely breeds in zoos around the world. Between 1970 and 1991 the population of pygmy hippos born in captivity more than doubled. The survival of the species in zoos is more certain than the survival of the species in the wild. In captivity, the pygmy hippo lives from 42 to 55 years, longer than in the wild. Since 1919, only 41 percent of pygmy hippos born in zoos have been male. While the common hippopotamus was known to Europeans since classical antiquity, the pygmy hippopotamus was unknown outside its range in West Africa until the 19th century. Due
Kozlov's pygmy jerboa April and May and the litter size averages three to five young. Kozlov's pygmy jerboa has a wide range and is a common species in suitable habitat. The population trend is not known but it is presumed to have a large total population and is present in several protected areas. No specific threats to this jerboa have been identified, and the International Union for Conservation of Nature has assessed its conservation status as being of "least concern". Kozlov's pygmy jerboa Kozlov's pygmy jerboa ("Salpingotus kozlovi") is a species of rodent in the family Dipodidae. It is found in northwestern China