Mammals
Author: Ray Bowers

Description:
Mammals are very unique animals. Mammals are the only kind of animal that have mammary (milk) glands to feed their young milk—mammals are actually named after these mammary glands. Mammals are also the only animal that have hair at some point in their lives. All mammals are warm blooded (homeothermic endotherms) animals and have a four-chambered heart (kind of like the human heart). Mammals are divided into three groups by how the reproduce (see Reproduction and Development). The three groups are: Monotremata, Marsupialia, and the Eutheria.

There are over 148 types of mammals living in New Mexico! Mammals can be found as small as the pygmy mouse (only about 4 inches long) and as large as the North American Bison (they can stand 6 feet tall at the shoulder).

Geographic Range:
Mammals live in many different kinds of places in New Mexico. They live in the rivers, like the River Otter, and they live in the highest mountains, like the Rocky Mountain Bighorn Sheep.

Reproduction and Development:
Mammals are divided into three groups based on the way they reproduce: The Monotremata (the platypus), Marsupialia (kangaroos and koalas) and Eutheria (humans and wolves).

The Monotremata lay eggs.

The Marsupialia give birth to their premature young and raise them in a pouch of skin at their bellys.

The Eutheria give birth to fully developed young.

Only one family of Marsupialia the Didelphidae (Opposums) live in New Mexico. All other mammals living in New Mexico belong to the group Eutheria.

Ecosystem Roles:
Mammals of all sizes have an important impact on their surrounding ecosystem. Many mammals are “keystone species” which means they have more of an effect on their surrounding environment than other species do. For example many mammals are “top-level” carnivores who sit at the top of the food chain and can eat many of their surrounding neighbors. Also smaller herbivore (plant eater) mammals, sometimes thought of as pests, can wipe out an entire crop of plants in their surrounding ecosystem.

Conservation:
As of 2002, 15 of the 148 mammals living in New Mexico are listed as endangered species .

Taxonomy:

Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Mammalia, Mammals, Mamíferos

Of the roughly 19 orders of mammals (considering the marsupials as a single order, which is probably not correct), the following orders occur in New Mexico:

Marsupialia: Marsupials (opossum)
Insectivora: Shrews, etc.
Chiroptera: Bats
Primates: Primates
Edentata: Armadillos, etc.
Lagomorpha: Hares, Rabbits, Pikas
Rodentia: Rodents
Carnivora: Carnivores
Perissodactyla: Odd-toed Ungulates (introduced)
Artiodactyla: Even-toed Ungulates

References:
Cockrum, E. Lendell; and Yar Petryszyn. 1992. Mammals of the Southwestern United States and Northwestern Mexico. Tucson: Treasure Chest Publications, 192 p.

Findley, James S. 1987. The Natural History of New Mexican Mammals. Albuquerque: University of New Mexico Press, 164 p.

Findley, James S.; Arthur H. Harris; Don E. Wilson; and Clyde Jones. 1975. Mammals of New Mexico. Albuquerque: University of New Mexico Press, 360 p.

Nowak, Ronald M. 1991. Walker's Mammals of the World, 5th ed. Baltimore: Johns Hopkins Univ. Press, 2 vols.

Related Terms: mammalia, mamíferos