Proboscis monkeys

Proboscis monkey

We are delighted that Thomas and Antje Gröner have taken over the sponsorship of the proboscis monkey (Nasalis larvatus).

The nose monkeys, which belong to the slender monkeys (subfamily Colobinae) and are unmistakable in appearance, originate from the coastal, swamp and mangrove forests of the Malaysian states of Sabah and Sarawak and the Indonesian Kalimantan on the island of Borneo as well as some islands off Borneo. The proboscis monkeys owe their name to the pronounced nose of the males. The monkey, which is found exclusively on Borneo, is also known as the "Dutch monkey" - locals see it as a caricature of the Dutch sailors who were once plantation owners on Borneo.

Proboscis monkeys are characterised by strong sexual dimorphism. The 73-76 cm tall and 20-24 kg heavy males have a long cucumber-shaped nose up to 10 cm long, which they even have to push aside with their hand when eating. Young animals and the females, which are only 61 - 64 cm tall and weigh around 10 kg, only have a small snub nose.
The otherwise rather sluggish monkeys stay in harem groups during the day, which usually consist of one male and six females and their young. At dusk, several harem groups often join together to rest - often resulting in loud rivalry fights.

Proboscis monkeys mainly eat young leaves, fruit and seeds as well as a small proportion of flowers. Sometimes they also eat tree bark and termite nests. Females have a gestation period of around 166 days and only give birth to one young at a time. As an adaptation to their water-rich habitat, proboscis monkeys can swim and dive well. They live in groups of one male with up to nine females and their young and, depending on the type of forest, these groups move through a range of 1.4 to 9 km2. Young males leave their family group at the age of around two years and form bachelor groups for a while. Natural enemies of the proboscis monkeys are clouded leopards (Neofelis nebulosa), various crocodile species (Crocodylus sp.) and the reticulated python (Python reticulatus)

Everywhere the habitat of the proboscis monkey at river mouths is acutely threatened by deforestation, forest fires, human settlements and along the coast by shrimp farms in the coastal swamps. According to recent estimates, there are only about 6000 proboscis monkeys left in Sabah and less than 1000 individuals in fragmented populations in Sarawak. In Indonesian Kalimantan, populations are somewhat more stable, but even there they are extinct, for example in the Pulau Kaget Nature Reserve in the south of the island.
Thus, proboscis monkeys are classified as a "threatened species" on the Red List of the International Union for Conservation of Nature (IUCN) and are listed on Appendix I of the Convention on International Trade in Endangered Species (CITES), which means that they may only be traded under exceptional circumstances.
Despite the establishment of several conservation reserves, population figures show a downward trend, as the proboscis monkey is not safe from hunters either. It is hunted for its meat and also for its bezoar stones, which are found in the proboscis of the proboscis monkey and are used in traditional Chinese medicine.