Proboscis Monkey

The proboscis monkey or long-nosed monkey is endemic to the island of Borneo. Borneo includes three countries: (1) Indonesia (which refers to its area on Borneo as Kalimantan) has about 73% of the island; (2) Brunei has about 1% of the island; and (3) Malaysia (which has two states, Sabah and Sarawak) has about 26% of the island. Brunei has one population, Sabah has two populations, Sarawak has about 1,000 in very patchy distributions and Indonesian Borneo has the majority.   

Proboscis monkey range from Wikipedia.

There is sexual dimorphism between males and females. The fur on its back is bright orange, reddish brown, yellowish brown or red and the underfur is light gray, yellowish or light orange. It has a bulgy stomach that resembles a pot belly and its toes are often webbed. Males are larger, 35 to 60 pounds, while females are 15 to 26 pounds. The male has a red penis with a black scrotum. What really is unique is the nose or proboscis. In males the nose can exceed 4 inches in length, is very bulbous at the end and can hang lower than the mouth (sometimes giving it the nickname the "Jimmy Durante monkey"). 

A photo of a male proboscis monkey from Wikipedia. I didn't get photos of any males. 

A photo of Jimmy Durante from Wikipedia.

The larger the nose, the greater the volume of the call, which is theorized to be an item of sexual selection by females. The nose of the female is much smaller and looks like Pinocchio's in the early stage before too many lies. 

I believe the monkey, upper right, is a male proboscis monkey carrying a young baby with a blue face. I believe this is the only male I photographed. Below it is a long-tailed macaque. 

We took a wooden klotok boat up the Sekonyer River into Tanjung Puting NP in Central Kalimantan. We saw lots of proboscis monkeys along the side of the river, but never got a good close view of one. Toward evening they would congregate in trees near the side of the river where they spent the night. Our first evening on the river we parked the klotok and watched the monkeys for about 30 minutes. 

It is most common along the coast and along rivers and is restricted to lowland habitats. It favors mangrove and riverine forests and is usually within a kilometer of a water source. It is the most aquatic primate: it can swim across rivers and can swim up to 66 feet underwater. It will even jump off of tree branches into water. 

Congregating in a tree getting ready to sleep. 

It eats primarily fruit (preferably unripe from January to May) and leaves (young preferred to mature from June to December), but will also eat flowers, seeds and insects. Groups usually sleep in adjacent trees and near rivers. 

It is listed as Endangered by the IUCN and the population decreased by more than 50% in the 36 to 40 years before 2008. The largest remaining populations are in Kalimantan (Indonesian Borneo). It is a beautiful and fascinating monkey. I really wish we could have gotten a closer look at them.