Study Suggests Gorillas Become More Violent in Crowded Forest
2020-11-12
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1Gorillas are very social animals -- up to a point.
2Crowded areas can make silverbacks more violent, scientists say.
3Silverbacks are adult male mountain gorillas that often have a white area across their backs.
4They are the leaders of gorilla families.
5Mountain gorillas are genetically similar to humans.
6The large animals spend most of their time sleeping, eating, and cleaning each other.
7They are mostly peaceful creatures.
8They live in parts of Uganda, the Democratic Republic of Congo, and Rwanda.
9Researchers recently studied 50 years of data from Rwanda.
10They found that as the number of gorilla family groups increased, so too did the of violent fights between them.
11Most often, silverbacks led the fights.
12Some gorillas died, especially infants, or babies.
13These deaths, in turn, slowed population growth.
14Damien Caillaud of the University of California, Davis, was a co-writer of the new study, published in Science Advances.
15"Males will fight to protect the females and infants in their group, and to acquire new females," he said.
16The study found that the amount of fighting was not a result of the total number of individuals in an area.
17What was important was the number of family groups in an area.
18Since the 1960s, mountain gorillas have been carefully studied and protected in central Africa.
19These animals almost died off in the 1970s.
20The population has since grown to just over 1,000 animals.
21Rich Bergl is a primatologist at the North Carolina Zoo.
22Bergl was not involved in the study.
23"Rarely do we think about how an animal's behavior and social structure can influence population size," Bergl said.
24He added, "But it turns out we should, especially for social animals like gorillas."
25Tara Stoinski was a co-writer of the new paper.
26She is also president of the Dian Fossey Gorilla Fund, a nonprofit group.
27"Everyone wants to know how many gorillas can live inside the protected habitat area. It turns out the answer depends partly on how they organize themselves socially," she said.
28While in Rwanda, Stoinski said she saw changes in gorilla behavior beginning about 2007.
29Around that time, three large family groups broke into many smaller family groups.
30The gorilla population grew and families spread out in Volcanoes National Park.
31There were about 10 family groups in the study area.
32The number of fights between them increased by three times.
33The number of infant deaths increased by five times.
34The population growth fell by half.
35The large family groups likely broke apart after the deaths of important silverback leaders, said Stoinski.
36"When these 'elder statesman' gorillas got older and died, the younger males weren't able to keep the groups together," she said.
37The study was based on data from about 400 gorillas in Rwanda between 1968 and 2017.
38I'm John Russell.
1Gorillas are very social animals -- up to a point. Crowded areas can make silverbacks more violent, scientists say. 2Silverbacks are adult male mountain gorillas that often have a white area across their backs. They are the leaders of gorilla families. 3Mountain gorillas are genetically similar to humans. The large animals spend most of their time sleeping, eating, and cleaning each other. They are mostly peaceful creatures. 4They live in parts of Uganda, the Democratic Republic of Congo, and Rwanda. 5Researchers recently studied 50 years of data from Rwanda. They found that as the number of gorilla family groups increased, so too did the of violent fights between them. Most often, silverbacks led the fights. 6Some gorillas died, especially infants, or babies. These deaths, in turn, slowed population growth. 7Damien Caillaud of the University of California, Davis, was a co-writer of the new study, published in Science Advances. 8"Males will fight to protect the females and infants in their group, and to acquire new females," he said. 9The study found that the amount of fighting was not a result of the total number of individuals in an area. What was important was the number of family groups in an area. 10Since the 1960s, mountain gorillas have been carefully studied and protected in central Africa. These animals almost died off in the 1970s. The population has since grown to just over 1,000 animals. 11Rich Bergl is a primatologist at the North Carolina Zoo. Bergl was not involved in the study. 12"Rarely do we think about how an animal's behavior and social structure can influence population size," Bergl said. He added, "But it turns out we should, especially for social animals like gorillas." 13Tara Stoinski was a co-writer of the new paper. She is also president of the Dian Fossey Gorilla Fund, a nonprofit group. 14"Everyone wants to know how many gorillas can live inside the protected habitat area. It turns out the answer depends partly on how they organize themselves socially," she said. 15While in Rwanda, Stoinski said she saw changes in gorilla behavior beginning about 2007. Around that time, three large family groups broke into many smaller family groups. 16The gorilla population grew and families spread out in Volcanoes National Park. 17There were about 10 family groups in the study area. The number of fights between them increased by three times. The number of infant deaths increased by five times. The population growth fell by half. 18The large family groups likely broke apart after the deaths of important silverback leaders, said Stoinski. 19"When these 'elder statesman' gorillas got older and died, the younger males weren't able to keep the groups together," she said. 20The study was based on data from about 400 gorillas in Rwanda between 1968 and 2017. 21I'm John Russell. 22Christina Larson reported on this story for the Associated Press. John Russell adapted it for Learning English. Caty Weaver was the editor. 23_____________________________________________________________ 24Words in This Story 25acquire - v. to get (something) : to come to own (something) : to come to have (something) 26primatologist - n. an expert in the branch of zoology that deals with primates - any member of the group of animals that includes human beings, apes, and monkeys 27habitat - n. the place or type of place where a plant or animal naturally or normally lives or grows 28elder - adj. of greater age 29We want to hear from you. Write to us in the Comments Section.