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Social correlates of reproductive success in the Gibbon colony on Ko Klet Kaeo, Thailand
Author(s) -
Brockelman Warren Y.,
Ross Bruce A.,
Pantuwatana Somsak
Publication year - 1973
Publication title -
american journal of physical anthropology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.146
H-Index - 119
eISSN - 1096-8644
pISSN - 0002-9483
DOI - 10.1002/ajpa.1330380280
Subject(s) - acre , demography , sex ratio , morning , reproductive success , natural (archaeology) , geography , ecology , zoology , biology , sociology , population , archaeology , agroforestry , botany
The free‐ranging colony of gibbons established on an island in the Gulf of Thailand by the SEATO Medical Research Laboratory in 1966–1967 was terminated in 1970. Out of the 20 gibbons originally introduced, four adults of each sex remained until near the end of the project. The four females each gave birth to one infant. In all cases the young were conceived five or more months after pairbonds and ranges had stabilized into a more natural‐like pattern, with fairly regular morning inter‐group vocal sessions and territorial boundaries between groups containing the most feral individuals. The maximum effective breeding density on the 60‐acre island was found to be about four or five pairs. The chances of reproductive success appear to be maximized in a free‐ranging colony containing several pairs by maintaining a one‐to‐one sex ratio and allowing enough space so that natural patterns of social behavior may be expressed. The amount of area required per group may vary with the individual gibbons and the environment, but we found it to be about ten acres.