Post by Gorilla king on Aug 8, 2021 10:03:56 GMT -5
The western lowland gorilla (Gorilla gorilla gorilla) is one of two subspecies of the western gorilla (Gorilla gorilla) that lives in montane, primary and secondary forest and lowland swampland in central Africa in Angola, Cameroon, Central African Republic, Republic of the Congo, Democratic Republic of the Congo, Equatorial Guinea and Gabon. It is the nominate subspecies of the western gorilla, and the smallest of the four gorilla subspecies.
The western lowland gorilla is the only subspecies kept in zoos with the exception of Amahoro, a female eastern lowland gorilla at Antwerp Zoo, and a few mountain gorillas kept captive in the Democratic Republic of the Congo.[2]
Description
The western lowland gorilla is the smallest subspecies of gorilla but still has exceptional size and strength. This species of gorillas exhibits pronounced sexual dimorphism. They possess no tails and have jet black skin along with coarse black hair that covers their entire body except for the face, ears, hands and feet. The hair on the back and rump of males takes on a grey coloration and is also lost as they get older. This coloration is the reason why older males are known as "silverbacks". Their hands are proportionately large with nails on all digits, similar to those of humans, and very large thumbs. They have short muzzles, prominent brow ridges, large nostrils and small eyes and ears. Other features are large muscles in the jaw region along with broad and strong teeth. Among these teeth are strong sets of frontal canines and large molars in the back of the mouth for grinding fruits[3] and vegetables.[4]
A male standing erect can be up to 1.8 m (5 ft 11 in) tall and weigh up to 270 kg (600 lb).[5] Males have an average weight of 140 kg (310 lb), females of 90 kg (200 lb).[6] Males in captivity, however, are noted to be capable of reaching weights up to 275 kg (606 lb).[4] Males stand upright at 1.67 m (5 ft 6 in), females at 1.5 m (4 ft 11 in).[7][5] According to the late John Aspinall a silverback gorilla in his prime has the physical strength of seven or eight Olympic weightlifters, but this claim is unverified. Western gorillas frequently stand upright, but walk in a hunched, quadrupedal fashion, with hands curled and knuckles touching the ground. This style of movement requires long arms, which works for western gorillas because the arm span of gorillas is larger than their standing height.
Albinism
The only known albino gorilla – named Snowflake – was a wild-born western lowland gorilla originally from Equatorial Guinea. Snowflake, a male gorilla, was taken from the wild and brought to the Barcelona Zoo in 1966 at a very young age. He presented the typical traits and characteristics of albinism typically seen in humans, including white hair, pinkish skin, light colored eyes, reduced visual perception and photophobia, and was diagnosed with non-syndromic albinism. The genetic variant for Snowflake’s albinism was identified by the scientists as a non-synonymous single nucleotide polymorphism located in a transmembrane region of SLC45A2. This transporter is also known to be involved in oculocutaneous albinism type 4 in humans. As it is a recessive allele, and his parents were an uncle and niece who were both carriers, this revealed the first evidence of inbreeding in western lowland gorillas.[8]
BehaviorSocial structure
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Western lowland gorilla groups travel within a home range averaging 8–45 km2 (3.1–17.4 sq mi). Gorillas do not display territorial behavior, and neighboring groups often overlap ranges.[9][10] The group usually favours a certain area within the home range but seems to follow a seasonal pattern depending upon the availability of ripening fruits and, at some sites, localised large open clearings (swamps and "bais"). Gorillas normally travel 3–5 km (1.9–3.1 mi) per day. Populations feeding on high-energy foods that vary spatially and seasonally tend to have greater day ranges than those feeding on lower-quality but more consistently available foods. Larger groups travel greater distances in order to obtain sufficient food.[3]
It is easier for males to travel alone and move between groups, as before reaching the age of sexual maturity, males leave their natal group and go through a “bachelor stage” that can last several years either in solitary or in a nonbreeding group.[11] However, while both sexes leave their birth group, females are always part of a breeding group. Males like to settle with other male members of their family. Their breeding groups consist of one silverback male, three adult females and their offspring.[11] The male gorilla takes on the role of the protector. Females tend to make bonds with other females in their natal group only, but form strong bonds with males. Males also aggressively compete for contact with females.[12]
The group of gorillas is led by one or more adult males. In cases where there is more than one silverback male in a group, they are most likely father and son. Groups containing only one male are believed to be the basic unit of the social group, gradually growing in size due to reproduction and new members migrating in. In the study done at Lope, gorillas harvest most of their food arboreally, but less than half of their night nests are built in trees.[13] They are often found on the ground and are made up of up to 30 gorillas. Western lowland gorillas live in the smallest family groups of all gorillas, with an average of four to eight members in each. The leader (the silverback) organizes group activities, like eating, nesting and travelling in their home range. Those who challenge this alpha male are apt to be cowed by impressive shows of physical power. He may stand upright, throw things, make aggressive charges, and pound his huge chest with open or cupped hands while barking out powerful hoots or unleashing a frightening roar. Despite these displays and the animals' obvious physical power, gorillas are generally calm and nonaggressive unless they are disturbed. Young gorillas, from three to six years old, remind human observers of children. Much of their day is spent in play, climbing trees, chasing one another and swinging from branches.[14]
Reproduction
Female western lowland gorillas do not produce many offspring due to the fact that they do not reach sexual maturity until the age of 8 or 9.[15] Female gorillas give birth to one infant after a gestation period of nearly nine months. Female gorillas do not show signs of pregnancy. Unlike their powerful parents, newborns are tiny—weighing four pounds—and able only to cling to their mothers' fur. These infants ride on their mothers' backs from the age of four months through the first two or three years of their lives.[14] Infants can be dependent on their mother for up to five years.[15]
A study of over 300 births to captive female gorillas revealed that older females tend to give birth to more male offspring as opposed to females under 8 years old. This pattern is likely to result from selective pressures on females to have males at a time when they can provision them most effectively, as male reproductive success probably varies more than that of females and depends more on the maternal role.[16]
Female western lowland gorillas living in a group led by a single male have been observed to display sexual behavior during all stages of their reproductive cycle and during times of non-fertility. Three out of four females have been observed to engaged in sexual behavior while pregnant and two out of three females have been observed to engage in sexual behavior while lactating. Females are significantly more likely to engage and participate in sexual behavior and activity on a day when another female is sexually active. It has been found that female western lowland gorillas participate in non-reproductive sexual behavior in order to increase their reproductive success through sexual competition. By increasing the female’s own reproductive success, she then decreases the reproductive success of other female gorillas, regardless of their reproductive state.[17]
Infanticide by adult male gorillas has occasionally been observed in this subspecies. Victims are never related to the killer. A male does this in order to have the opportunity to mate with the mother, who otherwise would have been unavailable while caring for her young offspring.[18]
Intelligence Use of tools
Their intelligence is displayed through their ability to fashion natural materials into tools that help them gather food more conveniently. While the use and manufacture of tools to extract ants and termites is a well-documented behavior in wild chimpanzees, it has never been observed in other great apes in their natural habitat and never seen to be done by other primates in captivity.
A female gorilla measuring depth of water with a branch at Nouabalé-Ndoki National Park in northern Republic of the Congo, an example of tool use in gorillas
In terms of manufacturing tools for the use of extracting for western lowland gorillas, they are able to adapt tools to a particular use by selecting branches, removing projections such as leaves and bark and adapting their length to the depth of the holes. It appears that they also anticipate the use of the tool since they begin with the biggest sticks available and progressively modify it until it is the perfect fit for inserting into a hole that contains food. This demonstrates the gorillas' acquisition of high level sensorimotor intelligence, similar to that of young human children.[19]
In the past, there was a gorilla that used a stick to measure the depth of water. In 2009, a western lowland gorilla at Buffalo Zoological Gardens used a bucket to collect water. In an experiment, one adult male gorilla and three adult female gorillas were given five-gallon buckets near a standing pool. Two of the younger females were able to fill the buckets with water. This is the first record of gorillas spontaneously using tools to drink in zoos.[20]
Communication
Another example of gorillas' significant intelligence is their ability to comprehend simple sign language.[14] In the mid-1970s, researchers turned their attention to communicating with gorillas via sign language. One gorilla, Koko, was born in San Francisco Zoo on July 4, 1971. Francine Patterson officially started working with Koko on July 12, 1972, with the goal of teaching her sign language. In the beginning, Patterson focused on teaching Koko only three basic signs: "food", "drink", and "more". Koko would learn signs through observation and from Patterson or one of her colleagues molding Koko's hands into the correct sign. On August 7, Patterson began a more formal routine of teaching Koko the signs, "food", "drink", and "more". In the couple weeks before that, Koko had been using gestures that seemed like attempts at the signs taught, but were deemed as coincidental and random and not intended for the actual purpose. Only two days after they started the more formal routine, Koko started responding consistently with the sign "food" when prompted to.[21] Within the first three months, Koko made 16 different combinations of signs and was also starting to form simple questions by using eye contact and different positioning of signs by the body. Koko mastered more than 1,000 signs and was said to be able to connect up to eight words together to form a statement expressing wants, needs, thoughts, or simple responses.[22][23]
There has been a study examining the ability of western lowland gorillas to give to and exchange with humans. This involved humans holding objects such as fruit, leaves or peanuts in one hand. Once the gorillas had given twigs to the humans, they would receive one of these objects. If the gorillas did not give them a twig, they would not get their desired object. The gorillas were shown to quickly learn about receiving rewards as mistakes made by the gorillas in the beginning of the experiments gradually decreased.[24]
en.m.wikipedia.org/wiki/Western_lowland_gorilla
The western lowland gorilla is the only subspecies kept in zoos with the exception of Amahoro, a female eastern lowland gorilla at Antwerp Zoo, and a few mountain gorillas kept captive in the Democratic Republic of the Congo.[2]
Description
The western lowland gorilla is the smallest subspecies of gorilla but still has exceptional size and strength. This species of gorillas exhibits pronounced sexual dimorphism. They possess no tails and have jet black skin along with coarse black hair that covers their entire body except for the face, ears, hands and feet. The hair on the back and rump of males takes on a grey coloration and is also lost as they get older. This coloration is the reason why older males are known as "silverbacks". Their hands are proportionately large with nails on all digits, similar to those of humans, and very large thumbs. They have short muzzles, prominent brow ridges, large nostrils and small eyes and ears. Other features are large muscles in the jaw region along with broad and strong teeth. Among these teeth are strong sets of frontal canines and large molars in the back of the mouth for grinding fruits[3] and vegetables.[4]
A male standing erect can be up to 1.8 m (5 ft 11 in) tall and weigh up to 270 kg (600 lb).[5] Males have an average weight of 140 kg (310 lb), females of 90 kg (200 lb).[6] Males in captivity, however, are noted to be capable of reaching weights up to 275 kg (606 lb).[4] Males stand upright at 1.67 m (5 ft 6 in), females at 1.5 m (4 ft 11 in).[7][5] According to the late John Aspinall a silverback gorilla in his prime has the physical strength of seven or eight Olympic weightlifters, but this claim is unverified. Western gorillas frequently stand upright, but walk in a hunched, quadrupedal fashion, with hands curled and knuckles touching the ground. This style of movement requires long arms, which works for western gorillas because the arm span of gorillas is larger than their standing height.
Albinism
The only known albino gorilla – named Snowflake – was a wild-born western lowland gorilla originally from Equatorial Guinea. Snowflake, a male gorilla, was taken from the wild and brought to the Barcelona Zoo in 1966 at a very young age. He presented the typical traits and characteristics of albinism typically seen in humans, including white hair, pinkish skin, light colored eyes, reduced visual perception and photophobia, and was diagnosed with non-syndromic albinism. The genetic variant for Snowflake’s albinism was identified by the scientists as a non-synonymous single nucleotide polymorphism located in a transmembrane region of SLC45A2. This transporter is also known to be involved in oculocutaneous albinism type 4 in humans. As it is a recessive allele, and his parents were an uncle and niece who were both carriers, this revealed the first evidence of inbreeding in western lowland gorillas.[8]
BehaviorSocial structure
Play media
Western lowland gorilla groups travel within a home range averaging 8–45 km2 (3.1–17.4 sq mi). Gorillas do not display territorial behavior, and neighboring groups often overlap ranges.[9][10] The group usually favours a certain area within the home range but seems to follow a seasonal pattern depending upon the availability of ripening fruits and, at some sites, localised large open clearings (swamps and "bais"). Gorillas normally travel 3–5 km (1.9–3.1 mi) per day. Populations feeding on high-energy foods that vary spatially and seasonally tend to have greater day ranges than those feeding on lower-quality but more consistently available foods. Larger groups travel greater distances in order to obtain sufficient food.[3]
It is easier for males to travel alone and move between groups, as before reaching the age of sexual maturity, males leave their natal group and go through a “bachelor stage” that can last several years either in solitary or in a nonbreeding group.[11] However, while both sexes leave their birth group, females are always part of a breeding group. Males like to settle with other male members of their family. Their breeding groups consist of one silverback male, three adult females and their offspring.[11] The male gorilla takes on the role of the protector. Females tend to make bonds with other females in their natal group only, but form strong bonds with males. Males also aggressively compete for contact with females.[12]
The group of gorillas is led by one or more adult males. In cases where there is more than one silverback male in a group, they are most likely father and son. Groups containing only one male are believed to be the basic unit of the social group, gradually growing in size due to reproduction and new members migrating in. In the study done at Lope, gorillas harvest most of their food arboreally, but less than half of their night nests are built in trees.[13] They are often found on the ground and are made up of up to 30 gorillas. Western lowland gorillas live in the smallest family groups of all gorillas, with an average of four to eight members in each. The leader (the silverback) organizes group activities, like eating, nesting and travelling in their home range. Those who challenge this alpha male are apt to be cowed by impressive shows of physical power. He may stand upright, throw things, make aggressive charges, and pound his huge chest with open or cupped hands while barking out powerful hoots or unleashing a frightening roar. Despite these displays and the animals' obvious physical power, gorillas are generally calm and nonaggressive unless they are disturbed. Young gorillas, from three to six years old, remind human observers of children. Much of their day is spent in play, climbing trees, chasing one another and swinging from branches.[14]
Reproduction
Female western lowland gorillas do not produce many offspring due to the fact that they do not reach sexual maturity until the age of 8 or 9.[15] Female gorillas give birth to one infant after a gestation period of nearly nine months. Female gorillas do not show signs of pregnancy. Unlike their powerful parents, newborns are tiny—weighing four pounds—and able only to cling to their mothers' fur. These infants ride on their mothers' backs from the age of four months through the first two or three years of their lives.[14] Infants can be dependent on their mother for up to five years.[15]
A study of over 300 births to captive female gorillas revealed that older females tend to give birth to more male offspring as opposed to females under 8 years old. This pattern is likely to result from selective pressures on females to have males at a time when they can provision them most effectively, as male reproductive success probably varies more than that of females and depends more on the maternal role.[16]
Female western lowland gorillas living in a group led by a single male have been observed to display sexual behavior during all stages of their reproductive cycle and during times of non-fertility. Three out of four females have been observed to engaged in sexual behavior while pregnant and two out of three females have been observed to engage in sexual behavior while lactating. Females are significantly more likely to engage and participate in sexual behavior and activity on a day when another female is sexually active. It has been found that female western lowland gorillas participate in non-reproductive sexual behavior in order to increase their reproductive success through sexual competition. By increasing the female’s own reproductive success, she then decreases the reproductive success of other female gorillas, regardless of their reproductive state.[17]
Infanticide by adult male gorillas has occasionally been observed in this subspecies. Victims are never related to the killer. A male does this in order to have the opportunity to mate with the mother, who otherwise would have been unavailable while caring for her young offspring.[18]
Intelligence Use of tools
Their intelligence is displayed through their ability to fashion natural materials into tools that help them gather food more conveniently. While the use and manufacture of tools to extract ants and termites is a well-documented behavior in wild chimpanzees, it has never been observed in other great apes in their natural habitat and never seen to be done by other primates in captivity.
A female gorilla measuring depth of water with a branch at Nouabalé-Ndoki National Park in northern Republic of the Congo, an example of tool use in gorillas
In terms of manufacturing tools for the use of extracting for western lowland gorillas, they are able to adapt tools to a particular use by selecting branches, removing projections such as leaves and bark and adapting their length to the depth of the holes. It appears that they also anticipate the use of the tool since they begin with the biggest sticks available and progressively modify it until it is the perfect fit for inserting into a hole that contains food. This demonstrates the gorillas' acquisition of high level sensorimotor intelligence, similar to that of young human children.[19]
In the past, there was a gorilla that used a stick to measure the depth of water. In 2009, a western lowland gorilla at Buffalo Zoological Gardens used a bucket to collect water. In an experiment, one adult male gorilla and three adult female gorillas were given five-gallon buckets near a standing pool. Two of the younger females were able to fill the buckets with water. This is the first record of gorillas spontaneously using tools to drink in zoos.[20]
Communication
Another example of gorillas' significant intelligence is their ability to comprehend simple sign language.[14] In the mid-1970s, researchers turned their attention to communicating with gorillas via sign language. One gorilla, Koko, was born in San Francisco Zoo on July 4, 1971. Francine Patterson officially started working with Koko on July 12, 1972, with the goal of teaching her sign language. In the beginning, Patterson focused on teaching Koko only three basic signs: "food", "drink", and "more". Koko would learn signs through observation and from Patterson or one of her colleagues molding Koko's hands into the correct sign. On August 7, Patterson began a more formal routine of teaching Koko the signs, "food", "drink", and "more". In the couple weeks before that, Koko had been using gestures that seemed like attempts at the signs taught, but were deemed as coincidental and random and not intended for the actual purpose. Only two days after they started the more formal routine, Koko started responding consistently with the sign "food" when prompted to.[21] Within the first three months, Koko made 16 different combinations of signs and was also starting to form simple questions by using eye contact and different positioning of signs by the body. Koko mastered more than 1,000 signs and was said to be able to connect up to eight words together to form a statement expressing wants, needs, thoughts, or simple responses.[22][23]
There has been a study examining the ability of western lowland gorillas to give to and exchange with humans. This involved humans holding objects such as fruit, leaves or peanuts in one hand. Once the gorillas had given twigs to the humans, they would receive one of these objects. If the gorillas did not give them a twig, they would not get their desired object. The gorillas were shown to quickly learn about receiving rewards as mistakes made by the gorillas in the beginning of the experiments gradually decreased.[24]
en.m.wikipedia.org/wiki/Western_lowland_gorilla
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