The female wolverine delays implantation; the egg cells float in the uterus for some time attaching to the uterus wall. Delayed implantation means that the young can be born at the right time, from January to April, regardless of when mating takes place. The female produces one litter every two or three years. She digs out a den in a snowdrift, in a tree hollow, or under a rock, where she has her young, called kittens. Two or three kittens are born each year. The kits are born furry and their eyes are closed. The kittens feed only from their mother for two or three weeks. During this time she rarely leaves them, feeding on food she has stored. Later the mother brings food to the den, but the kittens are eight to ten weeks old before they are weaned. They reach adult size by early winter but may stay with their mother until they are old enough to reproduce.
The wolverines need a large home territory of about 200 square miles. They need lots of shelters in rock crevices and among boulders to hole up during bad weather or to escape predators. Its huge, flat feet and long claws make the wolverine an excellent climber. Their feet also act as snowshoes and keep them from sinking into deep snow.
The wolverine is a shy animal that tries to avoid contact with humans. Human settlements and low birth rates have decreased the wolverine populations in North America. Wolverines are considered a rare and vulnerable species.
Structural and Behavioral Adaptations
Wolverines are so mean and so clever that trappers and outdoorsmen have called them Mountain Devil. Wolverines will follow their prey anywhere. They will follow them into caves, over mountains and dark places. It will follow for days if it has to. The wolverine is very strong and mischievous. They have been known to steal food. Wolverines are very brave they will fight almost anything.
A wolverine also has very small webs on its feet that help it swim. It has shorter fur and thicker skin in the winter that helps it keep warm. It hibernates for 2 months then stays awake for the rest of the time. It has sharp claws for digging.
One physiological adaptation of wolverine is their ability to response to seasonal change. Wolverines also have techniques of keeping warm and dry or away from the harsh coldness of the Taiga.
The water vole Arvicola terrestris, also known as the Northern water vole, is a semi-aquatic mammal that resembles a rat. In fact, water voles have often been mistermed, "water rats." It is also the largest and most famous of the British voles. Water voles have a short hair-covered tail, a blunt, rounded nose, and a small chubby face with small ears. They have a rich chestnut-brown coat, but individuals in Scotland often have black fur. The fur traps air that provides thermal insulation when swimming and they also possess flaps of skin in the ear that prevent water from entering. The body length is 12-20 cm and the weight is 150-300g.
They feed mainly on grasses and other plants near the water. At times, they will also consume fruits, bulbs, twigs, buds and roots. In Europe, when there is enough food to last water voles a long time, water vole "plagues" can take place. Water voles eat ravenously, destroying entire fields of grass and leaving the fields full of burrows, during these plagues. Voles may also eat insects, mollusks and small fish.
The water vole is active by day and night, and spends most of its time eating. It moves through grasses, sedges, willow shoots and other waterside plants, grasping the stems in its forepaws, tearing at them and biting out the best parts. A trail of discarded fragments and stumps is left behind. The water vole is, of course, a very good swimmer, paddling with all four legs, blunt nose held clear of the water. Its short dense undercoat, covered by the long outer fur, keeps the vole warm and dry which helps them to survive in a boreal forest.
Water voles have a few natural predators including herons, owls, pike, mink and otters. When chased underwater by an enemy, such as an otter, the vole kicks up a cloud of mud that acts like a smokescreen, giving the vole a chance to escape via one of its underwater burrow entrances.
Water voles generally live in burrows in the banks of slow-flowing watercourses where there is a high level of plant cover to provide them with shelter and food. They can also live in the banks of canals, ditches and ponds, and will make woven nests about the size of a small football in reeds and sedges. The burrow complex usually has at least one submerged entrance. The water vole is a very shy creature, requiring a great deal of cover around its burrows and over its runs. They will dive into the water if danger threatens. It is active during the day, unlike the rat which is largely nocturnal, but is rarely seen. Dawn and dusk are the best time to catch a glimpse of a water vole. Often the first clue that a water vole is present nearby is the 'plop' sound of them disappearing into the water from amongst the vegetation as you pass by. They have, however, become sufficiently tame in certain areas to steal the bait from fishermen's bait boxes.
This species lives for 2-3 years. The breeding season for water voles is from late March until early October, during which time all adults will hold discrete territories along the bank. Males hold relatively large territories which will encompass the territories of several females. Each territory is marked by a series of latrine sites, where the animals regularly leave their droppings and stamp to leave their scent.
The droppings are about 1cm long, regularly shapes and rounded at the ends. They are normally green in color and relatively odorless. When broken open they are clearly green inside. Another definitive sign of the water vole is a grazed 'lawn' often seen around the outside of a burrow on top of a bank. This is due to heavily pregnant females not venturing far from the burrows and simply popping their heads out and grazing around the edge of the burrow.
During the winter months, no breeding occurs and the animals no longer hold territories. They also become less active. This makes it more difficult to accurately determine whether water voles are present or not. The signs of rats will, however, still be visible and so care must be taken not to not identify a bank as being inhabited just by rats when water voles are present as well.
Structural and Behavioral Adaptations
The male water vole has a range of over 425 feet of water bank; the female somewhat less. To mark its territory, the male rakes its hind feet over its flank gland and pushes out a secretion that it then stamps into the ground with its hind feet. Water voles generally do not form large colonies. Those that live on dry land may form groups consisting of the adult pair and two generations of young. Water voles will fight if they are overcrowded, uttering high, shrill squeaks.
Water voles are expert swimmers, but are not particularly specialized for a life in the water, unlike beavers and otters but when chased underwater by an enemy such as this otter, they raised a cloud of mud that acts as a smoke screen.
Water voles also burrow into steep canal or riverside banks to form a complicated system of underground tunnels and nesting chambers. Intelligent voles construct their burrows on several levels to minimize the risk of flooding and at least one entrance will be below the water level for a fast escape if necessary. Water vole spotters should look out for closely grazed 'lawn' areas, often covered with neat piles of chopped grass, which are seen around burrow entrances.
One physiological adaptation of water vole is reproduction which may carry on through the summer into early winter, depending on the weather. In winter, a female, her daughter and unrelated males share a communal nest which is made of woven grass stems and usually below ground in a burrow, but they do not hibernate.
American pikas are tailless, have somewhat circular ears, are grayish to brown and are about the size of guinea pig. Their total length is 6.8 to 8.4 inches (170-210 mm); their weight is 5.3 to 6.2 ounces (150-175 grams). Like all lagomorphs, they have double upper incisors but the front pair is large and functional and the very small posterior pair is peg-like. Pikas have hair on their feet, an adaptation that gives them great traction as they scurry about rocks. Pikas are recognizable behaviorally. They dart about on talus…