Рефераты. Mammals






p> It seems that the success of spotted hyenas is ensured through individual and cooperative hunting and sharing of food between adults.
Cooperation also extends to communal marking and defense of the territory, in which both sexes play a similar role, whether or not they are related.
Competition within the clan can, however, be intense. The system of communication shows adaptations, which reduce aggression and coordinate group activities. Such competition probably provided the selection pressure whereby females evolved their large size and dominant position, which in turn relates also to levels of testosterone in the blood that are indistinguishable from those of the male. Thus female spotted hyenas are able to feed a small number of offspring alone and protect them from the more serious consequences of interference by other hyenas, particularly unrelated males.

WHY THEY LAUGH

Hyenas are often called "solitary," a label which obscures the fact that their social systems are among the most complex known for mammals.
Spotted hyenas employ elaborate meeting ceremonies and efficient long-range communication by scent and sound. Even when moving alone, spotted hyenas maintain some direct contact with their fellows. They respond to sounds, which are only audible to humans with the aid of an amplifier and headphones.

Calls audible to the unaided human ear include whoops, fast whoops, yells and a kind of demented cackle that gives this species its alternative name of laughing hyena. Whoop calls, in particular, are well-suited to long- range communication as they carry over several kilometers; each call is repeated a number of times, which helps the listener to locate the caller, and each hyena has a distinctive voice. Infant hyenas will answer the pre- recorded whoops of their mothers, but not those of other clan hyenas.

LIONS

AFRICAN LION: FAMILY CATS

Lions are among the most admired animals on earth. Their strength and beauty, combined with their bold nature, have fascinated people for ages.
In fact, the lion has often been called the "king of the beasts." And when you see a big male lion, with its magnificent main and proud walk, it's easy to understand why. Lions really do look like kings.

But lions don't always lead the easy lives of kings. They often need to work hard to survive. Lions are meat eaters, or carnivores, so they must hunt other animals for food. And sometimes prey is hard to find. When food is scarce, a lion may go for days without eating.

Lions are members of the big cat family, which includes tigers, leopards, and jaguars. The main difference between the big cats and all other cats is that generally big cats can roar but cannot purr. Other cats can purr but cannot roar.

The lion is one of the biggest cats in the world. Only the Siberian tiger is larger. A male lion may be 9 to 10 feet long (3 meters) and can weigh 500 pounds (227 kilograms) or more. Female lions are smaller. The average female is 7 to 8 feet long (2 l/2 meters) and weighs 270 to 350 pounds (140 kilograms).

Lions are different from most other cats in that they live in groups called prides. They hunt together, guard their territory together, and raise their young together. Lions that live in groups can catch more food than a single lion can. And they can protect themselves better. Also, lions that are born into groups have a large family to care for them.

There are two different kinds, or subspecies, of lions: the African and the Asiatic. Most of the lions in the world today are African lions.
These animals live on the grassy plains of Africa. The few Asiatic lions that remain live on a small wildlife preserve in India. There were once many other kinds of lions in the world but all of these are now extinct.

Lions sometimes climb high up into trees to rest on their branches and escape the biting insects below.

The body of a lion is made for catching prey. Most of the time, lions try to get very close to their prey before they attack it. Then they make a big leap and grab the prey. To help them get close without being seen, lions have golden-brown coats that blend in with the land around them. And to help them leap, they have strong muscles in their legs. A lion can leap
35 feet (10.5 meters) through the air in a single jump.

Lions do most of their hunting at night, so they have wonderful hearing and eyesight to help them find prey in the dark. Their hearing is so sharp, they can hear prey that is more than a mile away. Lions can turn their ears from side to side to catch sounds coming from almost any direction. When a lion is moving through tall grass, it may not always be able to see its prey -- but it can always hear it. The eyes of lions are the biggest of any meat-eating animal. Like the eyes of other cats, they are specially made for seeing at night.

Lions often work together when they hunt. By doing this, they increase their chances of getting food. A lion that hunts alone may have a hard time catching prey.

Most of the hunting is done by a team of females. They divide the job among them, with each female doing part of the work to catch the prey. Some of the females scare prey animals and make them run -- while other females lie in ambush to grab the fleeing animals.

The extra strength of a male is sometimes needed to bring down larger animals, like wildebeest or buffalo. And larger animals are the best prey, because they provide more meat.

No matter how good a lion is at hunting, it misses more prey than it catches. Sometimes lions will go for days without eating. If lions can't find enough of their regular prey, they will eat smaller animals like hares and tortoises -- and even porcupines.

When they can, lions get their food by taking it away from other animals. This is often easier than hunting. In some parts of Africa, much of the food that lions eat is taken away from hyenas. When food is really scarce, lions will eat almost anything they can find -- including snakes, locusts, termites, peanuts, fruit, and rotten wood.

Baby lions are called cubs. And like most baby animals they need lots of loving care. A lion cub is totally helpless at birth. It is blind and can barely crawl. And it weighs less than 5 pounds (2 kg).

Cubs are born in-groups called litters. Usually, there are three cubs in a litter. But sometimes there are as many as five. For the first few weeks of their lives, the cubs stay hidden in a safe place away from the pride. Then their mother brings them out to join the "family."

In a pride, all of the females help take care of the cubs. When one mother is away hunting, the other lions feed and watch over her young. But sometimes, all of the adults join the hunt. Then the cubs are hidden in the tall grass or among the rocks.

A cub is born with dark spots all over its body. Some people think that the spots may make it harder for predators to see the cubs when they are hidden.

A mother lion carries her babies in her mouth -- just like a motherhouse cat. To keep predators from finding the cubs, she moves them to a new hiding place every few days.

AFRICAN LION: FUTURE

Asiatic lions are endangered, and African lions have less living space than in times past. This is because people are taking away their homes, or habitats. The human population in Africa and Asia is rapidly growing, and people are turning more and more land into farms and ranches. This means that the lions have less food to eat and so it is harder for them to live.

Fortunately, wildlife organizations throughout the world are working hard to save the lions' habitats. And governments in both Africa and India have set aside special land where lions can live in safety.

AFRICAN LION: THE MANE CAT

Most experts agree that a lion will attack a human only if provoked.
But the experts also suggest that knowledge of the warning signs are mandatory for anyone who travels by foot in the bush. An angry lion will drop to a crouch, flatten its ears, and flick its tail tip rapidly from side to side. Low grunts and growls can often be heard; and just prior to a charge, the tail is jerked up and down. While these warning signs are important, it is perhaps of greater importance that a lion can bolt from a crouch and travel 40 yards in less than 2.7 seconds.

The lion is the largest of the African cats, weighing up to 200 kilograms (440 pounds). Of the big cats, only the tiger is of greater size.
The mane of a male lion is the most distinguishing characteristic of the species, although a small percentage of lionesses also have manes. The mane adds to the apparent size of a male lion, and it is believed that the mane provides added protection during male-to-male combat. The mane begins to develop at about one year of age but remains short and scraggly until the male is three or four years old. Another physical characteristic of lions is the tuft of long hairs at the end of the tail. This black tassel occurs in both males and females. Often, when females have cubs or are being courted by males, the tail tassel is carried high above the ground.
Researchers believe that this behavior allows cubs or males to maintain visual contact with the female when she moves through dense vegetation.
Fortunately for us, it is also an excellent way for humans to maintain visual contact.

LION: NO LONGER KING

You may have believed that African lions are the kings of the jungle.
Well, that's just not true. But the reason isn't because lions aren't the lordly animals that you thought them to be; it's just that lions don't live in the jungle. They live in the open savannas in Africa, which are grassy plains with a few scattered trees.

Lions, of course, are big cats, but they're different from tigers, leopards and other big cats because they are very social animals. They live in a group called a "pride," which can have as many as 35 lions in it.
Adult female lions, or lionesses, and cubs make up most of each pride, although two or three adult males live in it, too.

Hunting is how the lions get their food. They eat animals such as zebras, gazelles, hartebeests, gnus and even buffalo. Lionesses do most of the hunting but when it comes to eating, the adult males get their share first.

Lions often hunt together. A couple of lions may chase the prey and herd it toward other lions hiding in the grass. Then the hiding lions leap out and ambush the prey.

When lions eat, they often eat a whole lot of meat all at once. It's possible for a wild lion to eat up to 40 pounds of meat at one sitting. But then it may fast for several days and not eat anything. While it's fasting, the lion may be very, very lazy and just sleep a lot ... until its time to eat again.

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