47 résultats pour "endangered"
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Endangered Species - biology.
Red List database assesses the status of, and threats to, animal species worldwide. To add to this and other biodiversity databases, nongovernmental organizationssuch as Conservation International and World Wildlife Fund conduct periodic rapid assessments (focused, intensive evaluations) of biodiversity in varioushotspots— regions like Madagascar that are both rich in endemic species and environmentally threatened. This information is used in the administration of international agreements such...
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Extinction (biology) - biology.
III ROLE OF MASS EXTINCTION IN EVOLUTION Historically biologists—most famous among them British naturalist Charles Darwin—assumed that extinction is the natural outcome of competition between newlyevolved, adaptively superior species and their older, more primitive ancestors. These scientists believed that newer, more highly evolved species simply drove less well-adapted species to extinction. That is, historically, extinction was thought to result from evolution. It was also thought that this...
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Conservation.
cancers, Hodgkin’s disease and leukemia. Unfortunately, human activities have greatly reduced biodiversity around the world. The 20th century encompasses one of the greatest waves of extinction, orelimination of species, to occur on the planet. The greatest threat to biodiversity is loss of habitat as humans develop land for agriculture, grazing livestock, industry,and habitation. The most drastic damage has occurred in the tropical rain forests, which cover less than seven percent of the Earth’...
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Biodiversity.
a common molecule, ribonucleic acid (RNA), and most also have deoxyribonucleic acid (DNA). These molecules direct the production of proteins—molecules responsiblefor the structure and function of virtually all living cells. This is the evolutionary chain of life. All species are descended from a single common ancestor. From that ancient single-celled microbe, all inherited RNA. As time goesby, species diverge and develop their own peculiar attributes, thus making their own contribution to biodiv...
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Biodiversity - biology.
a common molecule, ribonucleic acid (RNA), and most also have deoxyribonucleic acid (DNA). These molecules direct the production of proteins—molecules responsiblefor the structure and function of virtually all living cells. This is the evolutionary chain of life. All species are descended from a single common ancestor. From that ancient single-celled microbe, all inherited RNA. As time goesby, species diverge and develop their own peculiar attributes, thus making their own contribution to biodiv...
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Monkey (animal) - biology.
traveling in troops, often take turns acting as sentinel, making specific alarm calls to alert their companions to approaching danger. In trees, monkeys have other waysof outwitting their enemies. Capuchins, for example, sometimes fend off inquisitive predators by urinating on them from high above or by jumping up and down tomake dead branches fall on the predators. Most monkeys can breed at any time of the year, so their troops often contain young of many different ages. Courtship is typically...
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Blue Whale - biology.
Mature females may give birth once every two or three years. The gestation period lasts about 11 months. A single young is usually born the following spring; twins arerare. The females migrate to warm regions to give birth. The young nurse for seven or eight months, gaining as much as 90 kg (200 lb) per day. VII CONSERVATION STATUS Blue whales were not targeted by the whaling industry until the late 1800s after faster steam-powered ships were developed. The peak slaughter of blue whalesoccurre...
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Koala - biology.
V REPRODUCTION Female koalas become sexually mature around 18 to 24 months of age. They can produce one offspring a year until they reach about 13 years of age. Males begin toproduce sperm around age 2 and, in the absence of older, stronger males, they may breed at that young age. More often, however, a male must grow big enough tocompete with other males for females, and mating generally begins for males at about 4 years of age. The breeding season for koalas is from October to May, during the...
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Cheetah - biology.
animals such as zebras. Unlike most cats, cheetahs hunt during the day, when lions and hyenas that compete with them for prey are less likely to be active. Still,scientists in Tanzania have observed that cheetahs lose 10 to 13 percent of their kills to lions and hyenas. Alerted by the panic of a gazelle herd or by the circling ofvultures, lions and hyenas close in and easily drive the more timid cheetah away from a fresh kill. A cheetah usually stalks prey to within about 10 m (about 33 ft) and...
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Colombia - country.
In Bogotá the average high temperature in January is 20°C (68°F), and in July the average high is 19°C (65°F). The highs for the same months in Barranquilla are 32°C(89°F) and 33°C (91°F). Throughout the year, three-month periods of rain and dry weather alternate. Along the Pacific coast precipitation is heavy. At Bogotá the annual rainfall averages about1,060 mm (about 42 in), and in Barranquilla it averages about 800 mm (about 32 in). Dry weather prevails on the slopes of the Cordillera Orient...
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Québec - Geography.
facilities. Tributaries south of the St. Lawrence include the Richelieu, the Saint-François, and the Chaudière rivers, which are only a few hundred kilometers long. TheRimouski and Matane rivers, also south of the St. Lawrence, are popular areas for recreation and salmon fishing. In the Canadian Shield, the longest rivers are theRupert, Eastmain, Grande Baleine, and La Grand-Rivière, which is the site of a huge hydroelectric complex. C Coastlines Québec has two systems of saltwater coastline. O...
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Québec - Canadian History.
facilities. Tributaries south of the St. Lawrence include the Richelieu, the Saint-François, and the Chaudière rivers, which are only a few hundred kilometers long. TheRimouski and Matane rivers, also south of the St. Lawrence, are popular areas for recreation and salmon fishing. In the Canadian Shield, the longest rivers are theRupert, Eastmain, Grande Baleine, and La Grand-Rivière, which is the site of a huge hydroelectric complex. C Coastlines Québec has two systems of saltwater coastline. O...
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Eagle - biology.
States, is a member of this group found only in North America. It is named for its snow-white head. However, the name bald does not refer to a lack of feathers but comes instead from an outdated word meaning marked with white, as in piebald. The adult bald eagle is blackish brown, with a white head and tail. Its bill, legs, and feet are bright yellow. The bill, which is longer and heavier than the gray bill of golden eagles, is useful for piercing the skin of fish. Bald eagles vary in size....
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Wolf - biology.
VIII RED WOLF The red wolf is smaller than the gray wolf. An adult red wolf stands about 65 cm (about 2 ft) high at the shoulder, measures 100 to 130 cm (3 to 4 ft) in lengthexcluding the tail, and weighs 20 to 36 kg (45 to 80 lb). It has long legs and ears and its head is not as wide as that of the gray wolf. The coat of red wolves varies incolor from light tan to black with reddish head, ears, and legs. Scientists have debated whether the red wolf is a subspecies of the gray wolf, a separate...
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Reptiles.
to find mates. A male turtle may stroke a female’s face with his front limbs. Most female reptiles make nests and lay eggs. A few lizards and snakes give birth to live young. All baby reptiles can live on their own as soon as they hatch. But most baby reptiles do not live morethan a few months. Birds, snakes, and mammals eat them. Sharks hunt baby sea turtles. Reptiles can live a long time if they don’t get eaten. Some tortoises may live up to 150 years. Alligatorscan live more than 70 years. Sm...
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Rattlesnake - biology.
Rattlesnakes are declining in number. The greatest threat to their survival is the destruction of their habitats. Snakes also suffer when their habitats are divided intofragments separated by roads, farms, housing developments, and shopping malls, making it harder for them to find mates, food, and breeding sites. In addition, tensof thousands of rattlesnakes are collected and killed each year by hunters who sell their patterned skin so that it can be made into such products as boots, ties, andbe...
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Wyoming (state) - geography.
The basins, which lie in the rain shadow of mountains, are very dry, with an average annual precipitation of about 250 mm (about 10 in) or less; the Great Plains regionhas an annual average of about 380 mm (about 15 in), and the Black Hills region receives slightly more. Thunderstorms and hailstorms are relatively frequent insummer. The annual snowfall ranges from about 500 mm (about 20 in) in the Bighorn Basin to well over 5,100 mm (over 200 in) in the higher mountains, where annualprecipitatio...
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Wyoming (state) - USA History.
The basins, which lie in the rain shadow of mountains, are very dry, with an average annual precipitation of about 250 mm (about 10 in) or less; the Great Plains regionhas an annual average of about 380 mm (about 15 in), and the Black Hills region receives slightly more. Thunderstorms and hailstorms are relatively frequent insummer. The annual snowfall ranges from about 500 mm (about 20 in) in the Bighorn Basin to well over 5,100 mm (over 200 in) in the higher mountains, where annualprecipitatio...
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Zebra - biology.
C Life Span Captive zebras have lived into their late 30s. Life expectancy in the wild, where predators abound, is probably not much more than 12 years. IV SOCIAL BEHAVIOR Like horses, zebras have large brains and a wide variety of social behaviors. Although they cannot match the overall intelligence of mammals that hunt, zebras interactwith each other in complex ways. Zebras usually live in groups known as herds, but the social structure of these groups depends on the species. The plains zeb...
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Vietnam - country.
E Natural Resources Vietnam’s most valuable natural resource is its land, particularly the fertile, alluvial soils in the Red and Mekong deltas. Some 29 percent of the land is currently beingcultivated. Vietnam has some valuable mineral resources, including gold, iron, tin, zinc, phosphate, chromite, apatite, and anthracite coal. Most deposits are located in the northernpart of the country. Few attempts were made to extract these minerals until the French takeover of Vietnam at the end of the 1...
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Environment.
escape into space of the infrared energy radiated back out by Earth. This process is referred to as the greenhouse effect. These gases, primarily carbon dioxide,methane, nitrous oxide, and water vapor, insulate Earth’s surface, helping to maintain warm temperatures. Without these gases, Earth would be a frozen planet with anaverage temperature of about -18°C (about 0°F) instead of a comfortable 15°C (59°F). If the concentration of these gases rises, they trap more heat within theatmosphere, caus...
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Bear - biology.
programs sponsored by zoos or other breeding centers have attempted to breed giant pandas in captivity, although most of these programs have proved unsuccessful.Among the difficulties faced by captive breeders has been the problem of encouraging a female giant panda to mate with a selected male during the two to three daysof the year when she is most fertile, a period known as estrus. B Spectacled Bear Creamy-white rings surrounding the eyes give the spectacled bear its name. Its shaggy coat of...
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National Parks and Preserves.
Some ibex raised in Italy’s 700 sq km (220 sq mi) Gran Paradiso National Park (1922) were transferred to aid herd restoration elsewhere in the country. Switzerlandreturned lynx to Swiss National Park to keep red deer populations in check. The growth of national parks also enabled many European countries to restore forests thathad given way to industrialization by the early 20th century. Africa’s wildlife was hunted heavily from the late 19th century well into the 20th century. By 1920 big-game h...
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Elephants.
ARE ELEPHANTS ENDANGERED? African and Asian elephants are now endangered species. People killed elephants for their ivory tusks.People destroyed the forests and grasslands where elephants lived. In the early 1900s, there werebetween 5 million and 10 million elephants living in the wild. By 1979, there were only 1.3 million.Another 600,000 African elephants were killed for their ivory tusks between 1979 and 1989. In 1989,many countries banned ivory sales and took other steps to protect elephants....
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Alligators and Crocodiles.
During cold winters, alligators bury themselves in mud. There they can hibernate until spring. WHERE CROCODILES LIVE Four species of crocodiles live in the Americas. These crocodiles are found in southern Florida, Cuba andother Caribbean islands, southern Mexico, Central America, and northern South America. The Indo-Pacific crocodile lives along the seacoasts of India, southern China, Malaysia, and Australia.The swamp crocodile is found in the lakes and rivers of India. The Nile crocodile lives...
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Monkeys.
Female monkeys usually give birth to only one baby at a time. The baby stays with its mother while itfeeds on her milk. In many species, the females stay with their mother’s family group for life. Malesoften leave their mother’s family group when they grow up. Compared to other animals, monkeys live a long time. It’s hard to know how long a monkey in the wildwill live. But some monkeys in zoos have lived to be more than 50 years old. WHAT DO MONKEYS EAT? What a monkey eats depends on the size of...
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Ape - biology.
previous infant has been weaned. This process—like all aspects of ape development—takes a remarkable length of time. A gibbon is weaned by the age of about 2years, while chimps take more than 4 years. Like young monkeys, young apes are carried by their mothers. They either cling to the mother's belly or, in the case ofolder chimps, ride on her back. In great apes, infant care is largely the job of the females, while in some gibbons the mother hands over responsibility to the fatherwhen the infan...
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Python (snake) - biology.
pythons are prey for monitor lizards, crocodiles, storks, eagles, and predatory mammals ranging from hyenas to leopards and other cats depending on the region. V PYTHONS AND HUMANS Modern humans have lived alongside pythons for thousands of years. The giant species have been treated with both reverence and fear. Pythons have been widelyassociated with fertility, water, and the Earth. Some African tribes have worshiped pythons as protective spirits. Among Aboriginal Australians the Rainbow Serpe...
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Seal (mammal) - biology.
remote lakes by swimming thousands of kilometers up rivers from the Arctic Ocean. A few other species such as ringed seals and harbor seals have been found livingyear-round in lakes and rivers near the coasts of Russia, Canada, and Alaska. IV DIET OF SEALS Most seals eat fish and sometimes squid. The leopard seal, an Antarctic species, may have the most diverse diet of all, commonly hunting penguins and other seabirds,smaller seals, as well as fish, squid, krill (small shrimplike crustaceans),...
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Sri Lanka - country.
acacias, and orchids are found in many areas. The animal life of Sri Lanka includes 88 species of mammals, 21 of which are threatened with extinction. The Asian elephant, cheetah, leopard, and several species ofmonkey are endangered and officially protected. The island’s many species of primates include the long-tailed langur, toque macaque, and slender loris. Other mammalsinclude the sloth bear, several species of deer, mongoose, and wild boar. Reptiles are numerous, with 144 known species. Som...
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Wisconsin (state) - geography.
-6° C (22° F) in the southeast, along the Lake Michigan shore. During winter extremely cold weather persists for several weeks at a time. C2 Precipitation Average annual precipitation ranges from 700 to 800 mm (28 to 32 in). Rainfall is generally heaviest during the spring and summer, and snowfall is generally moderatein the south, but can be quite heavy in the north. Thunderstorms, sometimes accompanied by devastating tornadoes, are common in spring and summer, particularly inthe southern part...
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Wisconsin (state) - USA History.
-6° C (22° F) in the southeast, along the Lake Michigan shore. During winter extremely cold weather persists for several weeks at a time. C2 Precipitation Average annual precipitation ranges from 700 to 800 mm (28 to 32 in). Rainfall is generally heaviest during the spring and summer, and snowfall is generally moderatein the south, but can be quite heavy in the north. Thunderstorms, sometimes accompanied by devastating tornadoes, are common in spring and summer, particularly inthe southern part...
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Switzerland - country.
formation over higher elevations. The wind reverses direction about sundown and moves down the valley as a cool downdraft. The foehn, which occurs during the wintermonths, is a dry and relatively warm airflow that is drawn northward over the Alps. The foehn can quickly melt snow and ice, increasing the risk of mudslides andavalanches. D Natural Resources Waterpower is the chief natural resource of Switzerland. The principal source of water is runoff from the considerable annual precipitation th...
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Michigan - geography.
The interior location of Michigan in the northern part of North America results in a continental climate, characterized by four definite seasons with moist, mild to hotsummers and snowy, cold winters. Winds off of Lakes Michigan and Superior in winter create heavy snow accumulations in nearby areas. The tempering effects of LakeMichigan account for the presence of the state’s famous fruit-growing belt along the lake’s shore. Since the water is colder than the land in spring, the westerly windspa...
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Michigan - USA History.
The interior location of Michigan in the northern part of North America results in a continental climate, characterized by four definite seasons with moist, mild to hotsummers and snowy, cold winters. Winds off of Lakes Michigan and Superior in winter create heavy snow accumulations in nearby areas. The tempering effects of LakeMichigan account for the presence of the state’s famous fruit-growing belt along the lake’s shore. Since the water is colder than the land in spring, the westerly windspa...
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Seals.
noises to find mates and scare away rivals. Some types of seals sing songs that last more than a minute. ARE SEALS ENDANGERED? Large sharks and killer whales hunt and eat seals. Polar bears kill seals on land and on ice in the Arctic.But people are the biggest threat to seals. People have hunted seals for food, skins, and blubber. The northern elephant seal has nearly died out. Hawaiian and Mediterranean monk seals are alsoendangered, and a third type of monk seal is already extinct. Many countr...
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Salmon (fish) - biology.
alarm and become one of the most important conservation issues in the Pacific Northwest. Less than 2 percent of the wild salmon population of the Columbia River Basin(including parts of Washington, Oregon, Idaho, Montana, Wyoming, and British Columbia) remains and only one individual sockeye salmon returned to the Snake Riverin Idaho in 1994. Coho salmon in the Snake River have been declared extinct by the U.S. Fish and Wildlife Service, as have 106 other salmon populations on the WestCoast. Man...
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Kangaroo - biology.
ungulates, they have evolved multi-chambered stomachs containing bacteria that can break down plant cell walls and release the nutritious cell contents. V SOCIAL ORGANIZATION Kangaroo social life is poorly understood, as few species have been studied in detail. Small species, such as potoroos, bettongs, and musky rat-kangaroos, tend to besolitary and widely dispersed, with a male's territory encompassing those of several females. The animals come together briefly for mating, and mother and offs...
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Wetland.
Other plants and animals have special adaptations suited for living in a wet environment. Most emergent plants have air spaces in their stems that enable oxygen to betransported to roots that grow in sediments with no oxygen. Some of the trees that grow in swamps form a set of roots above the soil surface or above the water thatallows them to get oxygen to the lower roots. In saltwater wetlands, specialized cells can limit the amount of salt that enters a plant, or specialized organs can excrete...
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Kenya - country.
threatens fish and other water life in the lake by depriving them of oxygen. Kenya is well known for its game parks—including Masai Mara Game Park and Tsavo National Park in the south, and Marsabit National Reserve in the north—whichattract large numbers of tourists and much revenue. Conservation of wildlife within reserves has thus received high priority. About 13 percent (2007) of Kenya’s totalland is protected. There are 229 (2004) threatened species in Kenya. Threatened habitats include the...
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Cambodia - country.
The population of Cambodia is 14,241,640 (2008 estimate). Population growth per year is estimated at 1.8 percent, one of the highest rates in Asia. The rate of infantmortality is also high. The population density is 81 persons per sq km (209 per sq mi), with the densest concentrations on the heavily cultivated central plain. Themountainous regions of the country, where malaria is widespread, are thinly populated, as are the poorly watered northern provinces. During the late 1970s, under thebruta...
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South Korea - country.
forest habitat, and overhunting. The Siberian tiger has not been sighted in the wild in South Korea since the 1920s; the Asiatic black bear can still be found in someremote mountain areas. Several species of deer are indigenous to the peninsula, including the roe deer, water deer, and Siberian musk deer. The musk deer, which hasbeen overhunted for its musk glands, is legally protected as a threatened species. Smaller mammals indigenous to the peninsula include the wild boar, red fox, badger,rabb...
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West Virginia - geography.
Forests, mostly of hardwood varieties, cover 79 percent of West Virginia. The principal commercial species are the oak, yellow poplar, maple, birch, beech, black walnut,hickory, and gum. Softwoods include pines and hemlock firs. Flowering trees include the wild crab apple, dogwood, hawthorn, and redbud. Among the many floweringbushes and plants are the rhododendron, which is the state flower, the laurel, blueberry, hepatica, wild geranium, and black-eyed Susan. Insects and disease, mostly introd...
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West Virginia - USA History.
Forests, mostly of hardwood varieties, cover 79 percent of West Virginia. The principal commercial species are the oak, yellow poplar, maple, birch, beech, black walnut,hickory, and gum. Softwoods include pines and hemlock firs. Flowering trees include the wild crab apple, dogwood, hawthorn, and redbud. Among the many floweringbushes and plants are the rhododendron, which is the state flower, the laurel, blueberry, hepatica, wild geranium, and black-eyed Susan. Insects and disease, mostly introd...
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Ontario - Geography.
governed Ontario’s initial settlement and development. The province’s most important river is the St. Lawrence. Its route was much improved and enlarged by dredgingand canal building in the mid-20th century. This enabled large ocean-going vessels to reach Great Lake ports ( see St. Lawrence Seaway). The Ottawa River was an important early route to the interior for fur traders and timber merchants. The Niagara River, because of its falls, is a great center of hydroelectric power as well as aninte...
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Ontario - Canadian History.
governed Ontario’s initial settlement and development. The province’s most important river is the St. Lawrence. Its route was much improved and enlarged by dredgingand canal building in the mid-20th century. This enabled large ocean-going vessels to reach Great Lake ports ( see St. Lawrence Seaway). The Ottawa River was an important early route to the interior for fur traders and timber merchants. The Niagara River, because of its falls, is a great center of hydroelectric power as well as aninte...
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Republic of Indonesia - country.
Mahakam in East Kalimantan and the Martapura and Barito in South Kalimantan. Most of these rivers originate in the island’s central massif (mountain mass) and meander through extensive swamps as they approach the coast. Settlements such as Samarinda and Banjarmasin cluster along the rivers, which serve ascommunication routes into the interior. The largest rivers on Sumatra drain from west to east into the Strait of Malacca. In the north, the Asahan River once linked trade between the Batak peo...