For mammal

Mammal

Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s the gestation

Gestation

Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....

 period is the time in which a fetus

Fetus

A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...

 develops, beginning with fertilization and ending at birth. The duration of this period varies between species.

Duration

For most species, the amount a fetus

Fetus

A fetus is a developing mammal or other viviparous vertebrate after the embryonic stage and before birth.In humans, the fetal stage of prenatal development starts at the beginning of the 11th week in gestational age, which is the 9th week after fertilization.-Etymology and spelling variations:The...

 grows before birth determines the length of the gestation period. Smaller species normally have a shorter gestation period than larger animals. For example, a cat's gestation normally takes 58–65 days while an Elephant's takes 645 days. However, growth does not necessarily determine the length of gestation for all species, especially for those with a breeding season

Breeding season

The breeding season is the most suitable season, usually with favourable conditions and abundant food and water, for breeding among some wild animals and birds . Species with a breeding season have naturally evolved to have sexual intercourse during a certain time of year in order to achieve the...

. Species that use a breeding season usually give birth during a specific time of year when food is available.

Various other factors can come into play in determining the duration of gestation. For humans, male fetuses normally gestate several days longer than females and multiple pregnancies gestate for a shorter period. Ethnicity may also lengthen or shorten gestation. In dogs there's a positive correlation between gestation time and a small litter size.

Gestation periods

chameleon

Chameleon

Chameleons are a distinctive and highly specialized clade of lizards. They are distinguished by their parrot-like zygodactylous feet, their separately mobile and stereoscopic eyes, their very long, highly modified, and rapidly extrudable tongues, their swaying gait, the possession by many of a...

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Mammal Mammal Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...	Gestation period (days)
baboon Baboon Baboons are African and Arabian Old World monkeys belonging to the genus Papio, part of the subfamily Cercopithecinae. There are five species, which are some of the largest non-hominoid members of the primate order; only the mandrill and the drill are larger...	187
bear Bear Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...  (black Black Black is the color of objects that do not emit or reflect light in any part of the visible spectrum; they absorb all such frequencies of light... )	210
bear Bear Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...  (grizzly Grizzly Grizzly may refer to:* Grizzly bear , a North American bear* Grizzly , a Marvel Comics character* Grizzly , a novel in Gary Paulsen's World of Adventure series... )	225
bear Bear Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...  (polar Polar Bear The polar bear is a bear native largely within the Arctic Circle encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is the world's largest land carnivore and also the largest bear, together with the omnivorous Kodiak Bear, which is approximately the same size... )	240
beaver Beaver The beaver is a primarily nocturnal, large, semi-aquatic rodent. Castor includes two extant species, North American Beaver and Eurasian Beaver . Beavers are known for building dams, canals, and lodges . They are the second-largest rodent in the world...	122
American Bison American Bison The American bison , also commonly known as the American buffalo, is a North American species of bison that once roamed the grasslands of North America in massive herds...	270
camel Camel A camel is an even-toed ungulate within the genus Camelus, bearing distinctive fatty deposits known as humps on its back. There are two species of camels: the dromedary or Arabian camel has a single hump, and the bactrian has two humps. Dromedaries are native to the dry desert areas of West Asia,...  (Bactrian Bactrian camel The Bactrian camel is a large, even-toed ungulate native to the steppes of central Asia. It is presently restricted in the wild to remote regions of the Gobi and Taklamakan Deserts of Mongolia and Xinjiang. A small number of wild Bactrian camels still roam the Mangystau Province of southwest... )	410
cat Cat The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...  (domestic Domestication Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been... )	58–67, Average 64
chimpanzee Chimpanzee Chimpanzee, sometimes colloquially chimp, is the common name for the two extant species of ape in the genus Pan. The Congo River forms the boundary between the native habitat of the two species:...	230–250
chinchilla Chinchilla Chinchillas are crepuscular rodents, slightly larger and more robust than ground squirrels, and are native to the Andes mountains in South America. Along with their relatives, viscachas, they make up the family Chinchillidae....	105–115
chipmunk Chipmunk Chipmunks are small striped squirrels native to North America and Asia. They are usually classed either as a single genus with three subgenera, or as three genera.-Etymology and taxonomy:...	31
3-6	cow	279–292
deer Deer Deer are the ruminant mammals forming the family Cervidae. Species in the Cervidae family include white-tailed deer, elk, moose, red deer, reindeer, fallow deer, roe deer and chital. Male deer of all species and female reindeer grow and shed new antlers each year...  (white-tailed White-tailed Deer The white-tailed deer , also known as the Virginia deer or simply as the whitetail, is a medium-sized deer native to the United States , Canada, Mexico, Central America, and South America as far south as Peru... )	201
dog Dog The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...  (domestic Domestication Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been... )	58–65, Average 61
donkey Donkey The donkey or ass, Equus africanus asinus, is a domesticated member of the Equidae or horse family. The wild ancestor of the donkey is the African Wild Ass, E...	365
elephant Elephant Elephants are large land mammals in two extant genera of the family Elephantidae: Elephas and Loxodonta, with the third genus Mammuthus extinct...  (Asian Asian Elephant The Asian or Asiatic elephant is the only living species of the genus Elephas and distributed in Southeast Asia from India in the west to Borneo in the east. Three subspecies are recognized — Elephas maximus maximus from Sri Lanka, the Indian elephant or E. m. indicus from mainland Asia, and E. m.... )	616
elk Elk The Elk is the large deer, also called Cervus canadensis or wapiti, of North America and eastern Asia.Elk may also refer to:Other antlered mammals:...  (Wapiti Elk The Elk is the large deer, also called Cervus canadensis or wapiti, of North America and eastern Asia.Elk may also refer to:Other antlered mammals:... )	240–250
European mink European mink The European mink , also known as the Russian mink, is a semi-aquatic species of Mustelid native to Europe. It is listed by the IUCN as Endangered due to an ongoing reduction in numbers, having been calculated as being more than 50% over the past three generations...	38-76
ferret Ferret The ferret is a domesticated mammal of the type Mustela putorius furo. Ferrets are sexually dimorphic predators with males being substantially larger than females. They typically have brown, black, white, or mixed fur...  (domestic Domestication Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been... )	41-42
fox Fox Fox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids , characterized by possessing a long narrow snout, and a bushy tail .Members of about 37 species are referred to as foxes, of which only 12 species actually belong to...  (red Red Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 630–740 nm. Longer wavelengths than this are called infrared , and cannot be seen by the naked eye... )	52
gerbil Gerbil A gerbil is a small mammal of the order Rodentia. Once known simply as "desert rats", the gerbil subfamily includes about 110 species of African, Indian, and Asian rodents, including sand rats and jirds, all of which are adapted to arid habitats...	22-26
giraffe Giraffe The giraffe is an African even-toed ungulate mammal, the tallest of all extant land-living animal species, and the largest ruminant...	420–450
goat Goat The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...  (domestic Domestication Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been... )	145–155
gorilla Gorilla Gorillas are the largest extant species of primates. They are ground-dwelling, predominantly herbivorous apes that inhabit the forests of central Africa. Gorillas are divided into two species and either four or five subspecies...	257
guinea pig Guinea pig The guinea pig , also called the cavy, is a species of rodent belonging to the family Caviidae and the genus Cavia. Despite their common name, these animals are not in the pig family, nor are they from Guinea...	56-74
hamster Hamster Hamsters are rodents belonging to the subfamily Cricetinae. The subfamily contains about 25 species, classified in six or seven genera....	15-18
hippopotamus Hippopotamus The hippopotamus , or hippo, from the ancient Greek for "river horse" , is a large, mostly herbivorous mammal in sub-Saharan Africa, and one of only two extant species in the family Hippopotamidae After the elephant and rhinoceros, the hippopotamus is the third largest land mammal and the heaviest...	225–250
horse Horse The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...	330–342
human Human Humans are the only living species in the Homo genus...	266
kangaroo Kangaroo A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...	42
leopard Leopard The leopard , Panthera pardus, is a member of the Felidae family and the smallest of the four "big cats" in the genus Panthera, the other three being the tiger, lion, and jaguar. The leopard was once distributed across eastern and southern Asia and Africa, from Siberia to South Africa, but its...	92–95
lion Lion The lion is one of the four big cats in the genus Panthera, and a member of the family Felidae. With some males exceeding 250 kg in weight, it is the second-largest living cat after the tiger...	108
llama Llama The llama is a South American camelid, widely used as a meat and pack animal by Andean cultures since pre-Hispanic times....	330
mink Mink There are two living species referred to as "mink": the European Mink and the American Mink. The extinct Sea Mink is related to the American Mink, but was much larger. All three species are dark-colored, semi-aquatic, carnivorous mammals of the family Mustelidae, which also includes the weasels and...	40–75
monkey Monkey A monkey is a primate, either an Old World monkey or a New World monkey. There are about 260 known living species of monkey. Many are arboreal, although there are species that live primarily on the ground, such as baboons. Monkeys are generally considered to be intelligent. Unlike apes, monkeys...  (rhesus Rhesus Macaque The Rhesus macaque , also called the Rhesus monkey, is one of the best-known species of Old World monkeys. It is listed as Least Concern in the IUCN Red List of Threatened Species in view of its wide distribution, presumed large population, and its tolerance of a broad range of habitats... )	164
moose Moose The moose or Eurasian elk is the largest extant species in the deer family. Moose are distinguished by the palmate antlers of the males; other members of the family have antlers with a dendritic configuration...	240–250
mouse Mouse A mouse is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse . It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles...  (domestic Domestication Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been...  white White White is a color, the perception of which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.White light can be... )	19
mouse Mouse A mouse is a small mammal belonging to the order of rodents. The best known mouse species is the common house mouse . It is also a popular pet. In some places, certain kinds of field mice are also common. This rodent is eaten by large birds such as hawks and eagles...  (meadow Meadow A meadow is a field vegetated primarily by grass and other non-woody plants . The term is from Old English mædwe. In agriculture a meadow is grassland which is not grazed by domestic livestock but rather allowed to grow unchecked in order to make hay... )	21
muskrat Muskrat The muskrat , the only species in genus Ondatra, is a medium-sized semi-aquatic rodent native to North America, and introduced in parts of Europe, Asia, and South America. The muskrat is found in wetlands and is a very successful animal over a wide range of climates and habitats...	28–30
opossum (Virginia Opossum Virginia Opossum The Virginia opossum , commonly known as the North American opossum or tlacuache in Mexico, is the only marsupial found in North America north of Mexico. A solitary and nocturnal animal about the size of a domestic cat, and thus the largest opossum, it is a successful opportunist... )	12–13
otter Otter The Otters are twelve species of semi-aquatic mammals which feed on fish and shellfish, and also other invertebrates, amphibians, birds and small mammals....	60-86
pig Pig A pig is any of the animals in the genus Sus, within the Suidae family of even-toed ungulates. Pigs include the domestic pig, its ancestor the wild boar, and several other wild relatives...  (domestic Domestication Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been... )	112–115
porcupine Porcupine Porcupines are rodents with a coat of sharp spines, or quills, that defend or camouflage them from predators. They are indigenous to the Americas, southern Asia, and Africa. Porcupines are the third largest of the rodents, behind the capybara and the beaver. Most porcupines are about long, with...	112
puma	90
rabbit Rabbit Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...  (domestic Domestication Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been... )	28–35, Average 31-32
raccoon Raccoon Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon , is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are...	63
rat Rat Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...	21-23
rhinoceros Rhinoceros Rhinoceros , also known as rhino, is a group of five extant species of odd-toed ungulates in the family Rhinocerotidae. Two of these species are native to Africa and three to southern Asia....  (black Black Black is the color of objects that do not emit or reflect light in any part of the visible spectrum; they absorb all such frequencies of light... )	450
seal Pinniped Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...	330
sea lion Sea Lion Sea lions are pinnipeds characterized by external ear-flaps, long fore-flippers, the ability to walk on all fours, and short thick hair. Together with the fur seal, they comprise the family Otariidae, or eared seals. There are six extant and one extinct species in five genera...  (California California California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area... )	350
sheep (domestic Domestication Domestication or taming is the process whereby a population of animals or plants, through a process of selection, becomes accustomed to human provision and control. In the Convention on Biological Diversity a domesticated species is defined as a 'species in which the evolutionary process has been... )	144–151
squirrel Squirrel Squirrels belong to a large family of small or medium-sized rodents called the Sciuridae. The family includes tree squirrels, ground squirrels, chipmunks, marmots , flying squirrels, and prairie dogs. Squirrels are indigenous to the Americas, Eurasia, and Africa and have been introduced to Australia...  (gray)	30–40
tiger Tiger The tiger is the largest cat species, reaching a total body length of up to and weighing up to . Their most recognizable feature is a pattern of dark vertical stripes on reddish-orange fur with lighter underparts...	105–113
whale Whale Whale is the common name for various marine mammals of the order Cetacea. The term whale sometimes refers to all cetaceans, but more often it excludes dolphins and porpoises, which belong to suborder Odontoceti . This suborder also includes the sperm whale, killer whale, pilot whale, and beluga...  (sperm Sperm The term sperm is derived from the Greek word sperma and refers to the male reproductive cells. In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell... )	480–590
wolf	60–68
wombat Wombat Wombats are Australian marsupials; they are short-legged, muscular quadrupeds, approximately in length with a short, stubby tail. They are adaptable in their habitat tolerances, and are found in forested, mountainous, and heathland areas of south-eastern Australia, including Tasmania, as well as...	26–28
zebra Zebra Zebras are several species of African equids united by their distinctive black and white stripes. Their stripes come in different patterns unique to each individual. They are generally social animals that live in small harems to large herds...  (Grant's Grant's Zebra The Grant's Zebra is the smallest of six subspecies of the Plains Zebra.-Distribution:The distribution of this subspecies is in Zambia west of the Luangwa river and west to Kariba, Shaba Province of the Democratic Republic of the Congo, north to the Kibanzao Plateau. In Tanzania north from... )	365