Small mammals or micromammals are a subdivision of

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

s based on their body mass and size. Different values have been used as the upper limit. The

International Biological Program The International Biological Program (IBP) was an effort between 1964 and 1974 to coordinate large-scale ecological and environmental studies. Organized in the wake of the successful International Geophysical Year (IGY) of 1957-1958, the Internat ...

me has defined small mammals as species weighing up to 5 kg. Alternatively, the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

(IUCN) groups the orders of

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are na ...

tree shrew The treeshrews (or tree shrews or banxrings) are small mammals native to the tropical forests of South and Southeast Asia. They make up the entire order Scandentia, which split into two families: the Tupaiidae (19 species, "ordinary" treeshrews) ...

s and

eulipotyphla Eulipotyphla (, which means "truly fat and blind") is an order of mammals suggested by molecular methods of phylogenetic reconstruction, which includes the laurasiatherian members of the now-invalid polyphyletic order Lipotyphla, but not the afr ...

ns (insectivores) together under the term small mammals. A significant majority of mammal species falls into the category of small mammals. They are found in a great range of habitats and climate zones.

Characteristics

Many small mammals have a short livespan and high fertility rate, resulting in a comparatively high variability in genetic composition. Their size leads to a reduced energy need for movement, but a high energy requirement for maintaining body temperature. This results in a high rate of food intake, using a wide range food sources. Their small size, together with frequently nocturnal or

crepuscular In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal, vespertine, or both. This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of daylig ...

activity, provide some protection against predators.

Research and conservation

The SSC Small Mammal Specialist Group (SMSG) of the IUCN "serves as the global authority on the world's small mammals" both with regard to research as well as conservation efforts.

References

Mammals {{Mammal-stub