Endangered Species: The gorilla

Transcription

1 Endangered Species: The gorilla By Gale, Cengage Learning, adapted by Newsela staff on Word Count 914 Level MAX Image 1. A male western lowland gorilla lost in thought. Photo from: Wikimedia Commons. The gorilla is considered to be one of the most intelligent land animals. It is the largest of the living primates, an order of mammals that also includes lemurs, monkeys, chimpanzees, orangutans and humans. When standing on its hind legs, an average male gorilla measures 5 to 5.75 feet high. It can weigh between 300 and 500 pounds. Females are smaller, measuring about 5 feet in height and weighing between 200 and 250 pounds. The color of a gorilla's coat varies from brown-gray to black. In males, the hair on the back begins to turn silver after 10 years of age. Males also have a large bone on top of their skull (called the sagittal crest) that supports their massive jaw muscles and gives them their distinctive high forehead. Both sexes have small ears, broad nostrils and a black, hairless face. Gorillas are active during the day, foraging for a variety of vines, herbs, leaves, fruits, roots and bark. During the wet season they tend to consume more fruit, while during the dry season their diet is composed primarily of fibrous vegetables and herbs. At night, gorillas build individual nests from branches and leaves in trees or on the ground. This article is available at 5 reading levels at 1

2 Highly social animals, gorillas form groups of five to 10 members, although larger groups have been documented. An average group is composed of a dominant mature male (called a silverback) and several females and their young. When young males in the group become mature (at about age 11), they leave to form their own groups. Young females also leave upon reaching maturity (at about age 8), joining lone males or other groups. Breeding between males and females can take place anytime during the year. After a gestation (pregnancy) period of 250 to 270 days, a female gorilla gives birth to a single infant. She will carry her infant for the first few months of its life, after which time it will begin to crawl and then walk. The young gorilla will remain dependent on its mother for up to three years. Almost half of all infant gorillas die before reaching maturity, being more vulnerable to predators, disease and many other dangers that adults can withstand. Female gorillas successfully raise only two to three young during their lives, which in the wild can be more than 40 years. Scientists have recognized two species of gorilla, each with two subspecies: the western gorilla (Gorilla gorilla), which includes the western lowland gorilla (Gorilla gorilla gorilla) and the Cross River gorilla (Gorilla gorilla diehli), and the eastern gorilla (Gorilla beringei), which includes the eastern lowland gorilla (Gorilla beringei graueri) and the mountain gorilla (Gorilla beringei beringei). This article is available at 5 reading levels at 2

3 Habitat And Population All four gorilla subspecies prefer forest habitats. The eastern lowland gorilla, having a population between 3,000 and 5,000, is found primarily in eastern Democratic Republic of the Congo. The mountain gorilla is found in the Virunga Mountains, a range of volcanic mountains stretching across the eastern Democratic Republic of the Congo, southwestern Uganda, and northwestern Rwanda. With a population of about 880, the mountain gorilla is one of the more endangered of the gorilla subspecies. The western lowland gorilla is found in Nigeria, Cameroon, the Central African Republic, Mbini (the mainland portion of Equatorial Guinea; also known as Río Muni), Gabon, the Republic of the Congo, and Angola. Its population has been estimated to be about 95,000, although it is most likely much lower than that. The Cross River gorilla is the rarest gorilla of all. It is restricted to a small area of highland forest along the Cross River, which crosses the border of Cameroon into Nigeria. This subspecies numbers only 250 to 300 individuals. This article is available at 5 reading levels at 3

4 History And Conservation For years, hunting has been the leading threat to gorillas. The animals are killed for food or trapped to become pets. Although current international agreements ban the selling or trading of gorillas as pets, illegal capture of the animals continues. The destruction of African forests is another serious threat to gorillas. More and more of their habitat has been cleared to create farms and to supply European and Asian timber companies. Logging roads, built deep into the forests, also allow hunters easy access to poach (illegally hunt) remaining gorillas. This article is available at 5 reading levels at 4

5 In 2007 the International Union for Conservation of Nature and Natural Resources (IUCN) downgraded the status of the western gorilla from endangered to critically endangered. In some areas, more than 90 percent of the western gorilla population had been killed, contributing to an overall decline in the species' population of about 60 percent between the mid-1980s and the middle of the first decade of the 21st century. The reasons for the decline were continued hunting and outbreaks among gorillas of the Ebola virus, a deadly and contagious virus discovered in Africa in the 1970s. The eastern gorilla's population is declining at a slower rate than the western gorilla, and it is listed as endangered. African countries within the gorilla's range are trying to establish conservation programs for the animal. These efforts, though, are often thwarted by limited finances and social and political unrest. One successful program has been the Mountain Gorilla Veterinary Project, which provides health care for injured and sick mountain gorillas in Rwanda, the Democratic Republic of the Congo, and Uganda. It is one of the few programs in the world to provide treatment to an endangered species in its natural habitat. This article is available at 5 reading levels at 5