Borneo has a hybrid 'mystery monkey,' and researchers are concerned

Baku, May 5, AZERTAC

An unidentified monkey spotted in Borneo is a rare hybrid between two different species that are competing for forest space, a new study suggests.

According to Live Science, researchers concluded that the "mystery monkey" is likely the offspring of a proboscis monkey (Nasalis larvatus) and a silvery langur (Trachypithecus cristatus) — two distantly related species that share the same habitat.

Coronavirus restrictions prevented the researchers from investigating the forest where the monkey lives, so instead the scientists analyzed photos that began appearing on social media in 2017. The monkey was initially photographed as a juvenile, but more recent photos from 2020 reveal that the animal is now a mature female and may have an infant of her own.

The hybrid monkey was spotted near the Kinabatangan River in Malaysian Borneo (the island is divided among three nations: Malaysia, Brunei and Indonesia), where the ranges of proboscis monkeys and silvery langurs overlap. But these two monkey species are visibly very different.

Adult proboscis monkeys have pinkish faces with elongated noses, while adult silvery langurs have black faces with shorter, flatter noses. Probosicis monkeys are also larger. A male proboscis monkey can grow up to 30 inches (76 cm) long and weighs 44 to 53 pounds (20 to 24 kg). Silvery langurs only reach about 22 inches (56 cm) long and weigh 14.5 pounds (6.6 kg) on average, according to the New England Primate Conservancy.

Both species live in groups composed of a dominant male and multiple females and their offspring. Males born into these groups are pressured to leave once they mature to start groups of their own, or take over another group. However, habitat decline is limiting the areas where these dispersing males can go, according to Ruppert.

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