Western gorilla
| Western gorilla | |
|---|---|
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| Male | |
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| Female with infant | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Primates |
| Suborder: | Haplorhini |
| Family: | Hominidae |
| Genus: | Gorilla |
| Species: | G. gorilla |
| Binomial name | |
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Gorilla gorilla (Savage, 1847) |
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| Subspecies | |
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| Western gorilla range | |
The western gorilla (Gorilla gorilla) is a great ape—the type species as well as the most populous species of the genus Gorilla.
Nearly all of the individuals of this taxon belong to the western lowland gorilla subspecies (G. g. gorilla), whose population is approximately 95,000 individuals. Only 250 to 300 of the only other western gorilla subspecies, the Cross River gorilla (G. g. diehli), are thought to remain.
Western gorillas are generally lighter colored than eastern gorillas. Western lowland gorillas can be brown or greyish with a yellowish forehead and also have an overhanging tip on their nose that is absent in eastern gorillas. Measurements of wild individuals show that mature males average 155 cm (61 in) in height, while mature females average 135 cm (53 in), weights of wild individuals have been rarely taken but captive western gorillas average 157 kg (350 lb) in males and 80 kg (180 lb) in females. The Cross River gorilla differs from the western lowland gorilla in both skull and tooth dimensions.
Western gorillas live in groups that vary in size from two to twenty individuals. Such groups are composed of at least one male, several females and their offspring. A dominant male silverback heads the group, with younger males usually leaving the group when they reach maturity. Females transfer to another group before breeding, which begins at eight to nine years old; they care for their young infant for the first three to four years of its life. The interval between births, therefore, is long, which partly explains the slow population growth rates that make the western gorilla so vulnerable to poaching. Due to the long gestation time, long period of parental care, and infant mortality, a female gorilla will only give birth to an offspring that survives to maturity every six to eight years. Gorillas are long-lived and may survive for as long as 40 years in the wild. A group's home range may be as large as 30 square km, but is not actively defended. Wild western gorillas are known to use tools.
Western gorillas' diets are high in fiber, including leaves, stems, fruit, piths, flowers, bark, invertebrates, and soil. The frequency of when each of these are consumed depends on the particular gorilla group and the season. Furthermore, different groups of gorillas eat differing numbers and species of plants and invertebrates, suggesting they have a food culture. Fruit comprises most of the gorillas' diets when it is abundant, directly influencing their foraging and ranging patterns. Fruits of the genera Tetrapleura, Chrysophyllum, Dialium, and Landolphia are favored by the gorillas. Low-quality herbs, such as leaves and woody vegetation, are only eaten when fruit is scarce. In the dry season from January to March, when fleshy fruits are few and far between, more fibrous vegetation such as the leaves and bark of the low-quality herbs Palisota and Aframomum are consumed. Of the invertebrates consumed by the gorillas, termites and ants make up the majority. Caterpillars, grubs, and larvae are also consumed in rarity.
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Wikipedia