Size matters – for the male proboscis monkey

Research finds a link between exaggerated, physical traits in male proboscis monkeys and attracting females.

A male proboscis monkey in Borneo

A male proboscis monkey in Borneo © Bioquatic Photo / McPhoto / Ullstein bild / Getty


A collaboration between scientists from Cardiff University, Danau Girang Field Centre, Kyoto University and Sabah Wildlife Department has found that female proboscis monkeys are most likely to be attracted to males who are endowed with larger… noses.

A protected species endemic to Borneo, the male proboscis monkey is easily distinguishable by its seemingly over compensatory facial feature and stunningly charismatic nature.

"We show evidence supporting both male-male competition and female choice as causal factors in the evolution of enlarged male noses," says Dr Sen Nathan, Assistant Director of Sabah Wildlife Department and Ph.D. student at Cardiff University and Danau Girang Field Centre.

Research found that nasal enlargement directly affected the resonance of male vocalisations and those with the larger facial features also tended to be the bigger, more dominant individuals with the greatest number of females in their harem.

Observations were gathered from four different locations, the first taking place in the Lower Kinabatangan Wildlife Sanctuary and the latter three in zoos.

Dr Ikki Matsuda, from Chubu University and Kyoto University, adds "In addition to finding that enlarged male noses serve as advertisements to females in mate selection, we also found that males with larger noses tended to have larger body mass and testis. This suggests that nose enlargement is a reliable predictor of social dominance and high sperm count."

Sabah Wildlife Department and Danau Girang Field Centre are now working on a 10-year action plan to create a state assisted conservation programme for the proboscis monkey.

Read the full paper in Science Advances.


Read more wildlife news stories in BBC Wildlife Magazine

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