Most primates are good climbers. Some primitive primates climb like early mammals, using claws to maintain their grip, but advanced primates, such as monkeys and apes, climb in another way. These animals have long legs, grasping toes, and flattened nails instead of claws. Instead of moving along the top of branches, they can also hang below them. Some species of primates—particularly gibbons—use a method of movement called brachiation. Hooking their hands over branches, they swing through the treetops. At top speed, a brachiating gibbon can move through the forest canopy as fast as a human can run.

On the ground, most heavily built mammals, such as badgers and bears, walk on the soles on their feet. This gait works well to maintain a grip, but it is not good for rapid movement. Hunting mammals, such as dogs and cats, have legs that are long and more slender. Instead of walking on their soles, these animals walk on the pads of their toes, with their heels staying high off the ground. This adaptation reduces friction and increases leverage, permitting much more rapid movement. Hoofed animals take this trend even further. These animals have very long legs, and they stand on the very tips of their toes. The combination of small, hard hooves and a long stride enables them to run quickly for long periods of time.

A small but varied assortment of mammals, including jerboas and kangaroos, have given up running on four legs, and instead hop on two. Hopping works best in open habitats, and is a surprisingly energy-efficient way of moving about. Every time a hopping mammal makes contact with the ground, tendons in its legs stretch like elastic. The energy from the stretched tendon helps to power the next jump.

Many forest mammals have evolved flaps of skin that act like wings enabling them to glide from tree to tree. Bats, however, are the only mammals capable of powered flight. A bat's wings are highly modified front legs, with four extremely long fingers that work like the spokes of an umbrella, opening up to support the wing. The remaining finger, which is much shorter, has a hooked claw and is often used for grooming the fur.

In the place of legs, marine mammals have evolved sturdy flippers. Seals have all four limbs and they use their hind legs to swim. In whales, however, the hind limbs have disappeared, leaving only tiny vestiges of bones hidden away inside the body. To power themselves, whales use tail flukes, horizontal flaps that are stiffened by tough fibers instead of bones. As a whale bends its backbone up and down, its flukes speed it through the water.

Given their speed and stamina, large mammals are able to exploit different habitats by migrating (see Animal Migration). In water, most toothed whales occupy the same range throughout the year, and it is unclear how far they migrate. Baleen whales, on the other hand, are well-known migrants. Most species give birth in tropical waters, and then migrate to their feeding grounds in the colder waters much closer to the poles.

On land, most migratory mammals are plant-eating species. They include tropical animals such as wildebeests and zebras, which migrate to take advantage of rain, and also Arctic species such as the caribou, which migrates between tundra and coniferous forest. Some herds travel up to 48 km (30 mi) a day, covering over 1600 km (1000 mi) in the course of a year.

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