Male Siberian ibex, a large and heavily built ibex living in Central Asia, are prone to group with community of the same sex, with the increase of their age, Chinese scientists found in their new study.

Male age plays an important role in this flocking behavior of the Siberian ibex. As males grow older, their segregation from females and younger males becomes stronger, their study showed.

"This behavior, social segregation as it called, will reach maximum values for males of nine years-old and older," said YANG Weikang, leading researcher of the study from Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences.

Adult Siberian ibex males were socially segregated from females all year round, except during the rutting season, when female and male ibex spent much more time in mixed-sex groups for mating, according to YANG.

The rutting season of Siberian ibex in the central Tianshan Mountains, where the study was carried out, usually starts in October and ends in December.

"Our study clearly shows that social factors play a key role in the sexual segregation of Siberian ibex," YANG said.

The Siberian ibex is a sexually dimorphic species, with females reaching their maximal growth around three years old, while males continue growing for six more years. Male Siberian ibex have a slower growth rate than females; however, they will grow up to two times larger and heavier than females in adulthood.

"Flocking with the same sex, age and size companions will guarantee the efficiency of their activities, due to similar body type and nutritional requirements. This may improve their chances of survival," said YANG.

Results of the study were published in the recent issue of Scientific Reports, entitled “The effect of male age on patterns of sexual segregation in Siberian ibex”.