From the lens of a veterinarian: The proboscis monkey

It would be hard to find a primate more distinctive than the proboscis monkey, an animal that is endemic to the island of Borneo. Due to its large belly and nose, it is sometimes known as the “Dutch monkey” in Indonesia as it has an alleged resemblance to the Dutch officials with big noses and bellies who were widespread throughout the country during the colonization period.

The nose of the male proboscis monkey can reach up to 7 inches in length. This large size in relation to the size of its head acts as a resonating chamber to enhance vocalizations and as a visual aid to attract females.

The large abdomen is the result of the bacteria in large stomach compartments, similar to a ruminant (they even supposedly chew their cud, although I never observed that). This digestive system allows them to digest the fibrous leaves that make up the bulk of their diet. Some of these leaves are toxic to other animals, giving the proboscis monkey a unique food source.

My first experience with a proboscis monkey was facilitated through my ears and not my eyes. It occurred in 1991 when I was with Uil Otto, a Dayak par excellence, that I met on my first Borneo trip. One day Mr. Uil (per Indonesian etiquette, you put Mr. in front of his first name) pulled me away from the group and said we are going canoeing together. I was in for a special treat, having the chance to spend the day with a man that was literally born in the rainforest.

Mr. Uil paddling us deep into the rainforest.

It was during that canoeing experience that I heard a loud thud in the trees along the river edge. Mr. Uil confirmed my suspicion of the sound being a proboscis monkey falling to the ground. Apparently, either due to the large size of the males in relation to the tree branches or a miscalculation by any one of them, occasionally these monkeys landed on the ground instead of landing in a different tree or branch. Seemingly no worse for wear, they would climb back up into the branches and go about their business of eating.

Back up a tree, staring at us, and acting as if nothing happened. The large size of the abdomen is obvious.

I wanted to photograph them in mid-flight after viewing their branch-to-branch acrobatics. I am an action-oriented wildlife photographer and love the challenge of photographing wildlife interacting with one another or their environment. It is easy to underestimate how fast wildlife move, so this was a big challenge for a 1990’s era (nothing digital here) manual focus camera shooting from a canoe on a moving river.

To capture them jumping from branch to branch, I had to anticipate the launch and then manually focus on this rapidly moving subject within 1 to 2 seconds. Needless to say, very few of my photos were in focus. The multitude of tangled branches, and the unpredictable nature of their jumping, added to the difficulty. Throw in a lens that was not powerful enough for a subject high in a tree, and you end up with poor-quality photos, judging by today’s standards.

At least I documented their jumping.

Even though my photos were disappointing, I was still having a ball thinking about my boyhood dream of visiting Borneo that turned into a real experience. This is an important point for me. I love being out in nature, in unique areas with unique wildlife, and if I do not get the photos I envision I am still happy, and now I have a reason to go back.

That reason came decades later on the same river when I took 3 people to Camp Leakey. Equipped with a fancy-schmancy (meaning expensive) new autofocus “digital-everything” camera and telephoto lens, it was time to see if I could improve upon my proboscis monkey photography. It was on me this time if I did not produce.

With this new equipment, the static photos of the monkeys staring at us as we motored by were easy to take. They are large animals, have nice contrast compared to the surrounding vegetation, and were curious enough of us to come out from the branches to get a better look.

This large male gave us a good view of his Jimmy Durante proboscis.

This younger male gave us a nice profile view of his smaller and still developing nose.

Their large “fermentation vat” stomachs are quite apparent.

Long appendages give them tremendous leverage as they jumped amongst the branches.

Now that the easy pictures were out of the way, it was time to see if I learned anything in those succeeding 20 years and if my equipment was worth the cost and the learning curve needed to get the action photos (the holy grail to me) of them jumping.

Patiently waiting for them to appear as I kept up the active process of pre-focusing while going downriver.

The modern professional digital camera I was using, especially with its advanced autofocus features, helped level the playing field for when they were jumping between branches and trees. It was still a big challenge since the monkey’s appeared out of nowhere sometimes, and the camera would not have enough time to autofocus. Also, as opposed to the static monkeys coming out and staring at us, the jumping monkeys were usually behind branches, and when the camera did focus, it was not on the monkey. In my early attempts, the end result was photos of leaves with an occasional monkey tail in it.

Wildlife photography, especially of wildlife on the move, is an active and dynamic process, so I stayed proactive and constantly pre-focused 20 to 40 yards ahead along the tree line as our klotok motored downstream. This gave the autofocus mechanism an added half of a second to do its job.

I kept at it, and in a short period of time I had the necessary “feel” for the ever-changing rainforest lighting and the jumping behavior of the monkeys, and was able to capture them frozen in the air.

A large male at takeoff.

Frozen in flight.

This link to my trip has many more photos of proboscis monkey’s, including complete sequences from takeoff to landing: https://lbah.com/wildlife-photography-blog/proboscis

The next primate I will talk about is the speedy, acrobatic white-bearded gibbon.