動物学：ニシゴリラは縄張り意識を持っているかもしれない

Groups of western gorillas may defend the centres of their home ranges against neighbouring groups, a study in Scientific Reports suggests. These findings may suggest that western gorillas are territorial.

Gorillas are widely assumed to be non-territorial due to their large home ranges (the areas in which they live and move), extensive overlap between the home ranges of different groups, and limited aggression between groups.

Robin Morrison and colleagues used large-scale camera trapping to monitor eight groups of western gorillas (113 individuals in total) across a 60 km2 area in the Republic of Congo. The authors determined the home ranges of each group and found that, although there is some overlap in the home ranges of different groups, gorillas tended to avoid feeding in areas that had been visited by another group that day. Avoidance was more likely the closer the area was to the central region of another group’s home range.

The authors suggest that gorillas may avoid the centres of other groups’ home ranges to prevent conflict as these regions may be defended by physical aggression or chest beating. They also suggest that larger groups may find it easier to defend central regions than smaller groups.

The findings contribute to a growing body of evidence suggesting that the social structures of gorillas are more complex than previously thought, as interactions between groups are influenced by social and familial relationships and territoriality.