title: Group size and structure in western lowland gorillas (Gorilla gorilla gorilla) at Mbeli Bai, Republic of Congo.
abstract: This paper describes the size and structure of western lowland gorilla groups visiting Mbeli Bai, a swampy forest clearing in northern Congo. An observation platform at the edge of the clearing was used over a 3-yr period, with gorillas visible for 1,681 hr. Data are presented on 14 groups and seven solitary males. Mean group size (excluding solitary males) was 8.4 +/- SD 4.3, and did not differ significantly from most other gorilla studies. All groups at Mbeli contained only one fully mature male and did not show evidence of fission-fusion or regular subgrouping. All emigrating males that remained in the population became solitary, and "bachelor" groups were not observed. Methodological issues are raised, including the classification of multi-male groups, and the demographic profiles of other populations are discussed in the light of results from Mbeli.
authors.affiliation: Wildlife Conservation Society, New York Zoological Society, Bronx, New York, USA. r.j.parnell@stir.ac.uk
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Parnell
mesh_terms: D000818:Animals; D003710:Demography; D005260:Female; D006071:Gorilla gorilla; D008297:Male; D011157:Population Dynamics; D012919:Social Behavior; D014197:Trees