Habitat Fragmentation Varying Effects on Two Species

Environmental Science Habitat Fragmentation: Varying Effects on Two Species The giant panda of China and the North American coyote are faced with a similar situation; their respective habitats are being destroyed or changed into smaller, isolated fragments. The effects of habitat destruction on the two species, however, are vastly different. Once found primarily in the northwest region of the United States, the coyote has adapted readily to changes caused by humans and has been steadily extending its range. The coyote can be found throughout the North American continent, extending from eastern Alaska to New England, and south through Mexico and Panama. It has even been sighted in urban areas. In contrast, the giant panda population has been steadily diminishing along with its respective habitat. Its population originally extended through the mountains of most of southern and eastern China and northern Vietnam, but by 1900, the area has been reduced to the Qinling Mountains. This area was further reduced as agricultural expansion broke it into separate regions in six mountain ranges. These isolated regions within six mountain ranges in China are the only places in nature that pandas can be found today. A recent report by the World Wildlife Fund stated the panda habitat has shrunk by 50 per cent in China’s Sichuan Province, home to the largest natural population of giant pandas (www.ecoworld.com). Why does a loss of habitat result in such a marked difference in the population of these two species? The answer lies in biological factors and adaptability. This paper will attempt to compare and contrast the major characteristics of each species, showing the relationship between these characteristics and population growth/decline. In addition, it will address possible human impact and interventions. Giant Panda It is easy to get a mental picture of a giant panda; the characteristic white and black markings, bear-like face and round body distinguish it from other animals. Pandas are large animals, ranging in size from 63 to 75 inches and weighing in between 150 -275 lbs (depending on gender). Pandas fit the defining characteristics of a K-selected, or equilibrium, species. Female pandas carry their young for approximately 135 days, and only one or two panda cubs are born to a mother each year. Young pandas are entirely dependent on the mother until they are weaned at about nine months; they leave their mothers when she conceives again, when they are about 18 months of age (www.animalinfo.org). Pandas are usually solitary creatures, though their home ranges can overlap with one another. They come together during mating season, which stretches from mid-March to mid-May. It is a well-known rumor that pandas have trouble reproducing; this may not be as true as we have come to believe. A World Wildlife Fund study reports “research shows that the giant panda may live longer in captivity, but that breeding success is greater in the wild” (www.ecoworld.com). Wild panda populations involved in long-term studies have shown to have reproductive rates similar to the thriving American black bears (Pandas –Ecology). Pandas consist almost entirely on a diet of bamboo, a plant that grows abundantly in the mountain ranges of China. Pandas are specialists; they have evolved with adaptations that aid in the process of eating and digesting bamboo and are, for the most part, restricted to this food source. Pandas might look like their bear relatives, but they are herbivores with flat, ridged teeth designed for crushing and grinding bamboo. Their strong jaws and cheek muscles help them chew the thick stalks. They have a moveable wrist bone that acts like a thumb, allowing the pandas to better grasp bamboo. Pandas’ digestive tracts are similar to carnivores, meaning they have trouble digesting the cellulose of bamboo. This leads to a need to consume large amounts of bamboo to sustain them. Bamboo is abundant in the rainy forest habitat of the pandas, and grows throughout the year. Pandas eat all parts of the bamboo plant, from its tough stalk to its leaves. Because bamboo is so low in nutrients, pandas spend nearly 10 to 12 hours feeding per day, and eat up to 80 pounds of bamboo in just one day. Bamboo plants grow to maturity, flower and produce seeds, and then die. The seeds slowly grow into large plants. While bamboo is abundant in the forest, it goes through dying periods, where all of the species in one area will bloom and die at the same time. This forces the pandas to migrate to another area to find more bamboo; as habitat fragmentation becomes more of an issue, it is increasingly difficult for pandas to migrate to other areas. Pandas are not restricted to one species of bamboo – they can eat 25 different types – but they usually eat only the few types that grow in their home range. (www.animalinfo.org). Coyotes A member of the dog family, the coyote is similar in shape and size to a collie. Coyotes can range from 20 to 50 pounds in weight, depending on where they live. The animals have a round, bushy tail that they carry straight out below their backs. High elevation coyotes have dark, thick, long hair with a white underbelly that becomes long and silky in the winter months. The animals have five digits on their forefeet and four on their hind feet, and walk with only their toes touching the ground. Coyotes are swift runners and can easily leap an average of eight feet. While still considered a Kselected species, coyotes are further along the continuum toward r-selected species than the giant panda because of a higher number of offspring and a shorter weaning period. Coyotes mate for life, and a female will usually bear a litter of 2 – 12 pups in the spring months. Cubs start eating solid food at about 3 weeks old and first hunt in groups led by the mother coyote at age 6 to 10 weeks. Within six months, the young coyotes are hunting alone (www.natureparkcom). Coyotes also have a shorter lifespan – an average of six years – than giant pandas. While they often hunt alone, coyotes will also travel in packs and work together to hunt and kill a larger animal. The howling associated with the coyote is used as a form of communication; coyotes howl or bark to warn of danger, to call pups, to celebrate or to threaten others. Coyotes have a highly developed sense of smell as well as acute hearing. These characteristics have enabled the coyotes to survive in both the wild and more populated areas (www.desertusa.com). Coyotes are extremely adaptable animals; they are generalists in the true sense of the word. While the typical coyote diet consists of small mammals, insects, reptiles, fruit and carrion, recent research suggests coyotes can exist on whatever the area offers in terms of food. Coyotes are opportunistic predators, with a wide variety of hunting techniques that they employ both day and night. Coyotes, like pandas, are elusive and tend to avoid human interaction. They are rarely seen, only heard. Coyotes have faced an additional threat that pandas have not; there have been numerous efforts to control the coyote population, producing an animal that is extremely alert and wary. As we have seen with pandas in captivity, animals that are in constant contact with humans soon become less afraid. Coyotes go out of their way to avoid humans, but as they become habituated to people, they will become bolder approaching people. Coyotes have started to discover urbanized areas are a good source of food; swimming pools, dog water dishes and ponds are convenient sources of water (www.desertusa.com). Stanley Gerht of Ohio State University studied the coyote population in greater Chicago over a six-year period. He found that urban coyotes tend to live longer than rural counterparts, living anywhere from parks to industrial areas. “A coyote living in urban Chicago has a 60-percent chance of surviving for a year, while a rural coyote has a 30 % chance of living for another year” (www.world-science.net). Gerht estimated there were up to 2,000 coyotes living in the greater Chicago area, and hypothesized that other urban areas might be experiencing similar coyote populations. The biological and behavioral differences of these two animals are the key to their ability to survive when faced with a changing habitat. As a K-selected and specialist species, pandas are neither resistant nor resilient to drastic changes in their habitat. Natural selection has resulted in the evolution of pandas with characteristics that help them to eat bamboo; if this major food source is eliminated, pandas cannot adapt quickly enough to survive. Their low reproduction rate also hinders chances of survival in a dwindling habitat. As the habitat fragmentation continues to isolate groups of pandas from one another, the species faces a new problem: a diminishing gene pool. This could lead to more genetic problems for the pandas. In contrast, coyotes are generalists who are not tied to any specific food source. They have evolved with a set of characteristics that allow them to adapt to a variety of habitats and diets. Coyotes have been able to thrive in urban areas and have benefited from the decline of their main predator, the wolf. This discussion begs the question, what role do humans have in protecting or controlling these species? While there are natural causes of habitat fragmentation, the habitat loss that has resulted in a diminishing panda population and an increased coyote population is due primarily to human impact. Pandas have existed in the mountains of East Asia for nearly three million years. Logging, agricultural expansion and human population growth into the panda habitat has reduced the habitats to small, isolated fragments. The pandas can no longer migrate to find new sources of bamboo if necessary. Today, great amounts of money and resources are poured into protecting pandas, especially those in captivity. Hosting a giant panda at a zoo cost an average of 2.6 million per year (Warren 48). The World Wildlife Fund has worked to protect pandas in the wild, as well. China has banned logging in natural forests and started a 10- billion dollar reforestation project. The government has also announced plan to invest a billion dollars a year over 30 years to expand the protected areas (Warren 53). At the same time, however, China is promising economic growth in the country’s poorest areas and dedicating one hundred billion dollars toward this program. The program includes construction, industry and tourism – and may overlap with the remaining panda habitat (Warren 53). Conversations also surround the issue of increasing coyote populations. There is an ongoing disagreement about the value of coyote – some believe it is necessary to preserve balance of nature. Those individuals with agricultural interests say the coyote population should be controlled so it does not kill livestock or poultry. The position of many biologists is a compromise; individual coyotes causing problems should be dealt with, but the species as a whole is not harmful (“The Coyote”). The issues and challenges surrounding habitat fragmentation are not going to go away. As the human population continues to increase and we continue to expand our own habitats, we inevitably affect the habitats of native species. The situations today with pandas and coyotes are primarily a result of human activity. By studying these two species, we can examine the extreme effects of our expansion. It is up to us to take responsibility for our actions.