Who's Who in the Owl Monkey Woods? 

When you do research it’s very important to be able to identify the individuals that you are observing quickly and accurately. Depending on the type of research you are conducting the level of individual identification varies. In some studies just differentiating between both sexes is enough however when studying owl monkeys it is impossible to tell apart a male from a female due to a lack of sexual dimorphism in this species. So in this case distinct features such as physical markings, scars, and differences in body structure may be used in identifying the subject.  At first when you start observing you have to try to spot noticeable physical differences of the individuals in the enclosure you may be watching. Because owl monkeys are active at night and the observations take place at night it’s hard to tell them apart by things like a slightly darker coat of one compare to the others house in the same enclosure, and because owl monkeys are so agile and quick it also gets challenging trying to identify them by their faces or the trident marks on the top of their heads, many times the monkeys are not facing you or keep still long enough for you to get a proper id and if these are the only physical characteristics you are basing your id on it may lead to problems in the future.

Owl monkeys are notoriously difficult to identify. Can you spot the male and female in this photo? It is very difficult to know without knowing the physical traits of each monkey. 

The most helpful physical characteristics to take note of before the start of the observation (for me at least) are; the size difference between the monkeys, if its large it could be a great help in identifying them. The tails are always good to look at, some of them being very short compare to their enclosure partners. The state of the coat should be noted also, some monkeys will have patches of fur missing from over grooming, nervous habits, or scars (this last one is rarely seen with this group of owl monkeys,) or the fur in the tail may be very different from their companions. Some of the monkeys also have large throat sacks that are very easily spotted. Some also have advance cataracts that give off a dull white reflection when the light hits them. If you look at Lucifer and Creamy you can see this large size difference, same with georgie and her companion. The most distinct difference in tail length is between Iago and Nina (Nina having the shortest tail in our collection). Cloe’s coat is a very striking example of a difference in coat estate, her lack of fur is due to over grooming by her partner which is thought to get better once she is switch enclosures. If you want to see a difference in the tail fur you have to look at Retsina’s family who has very distinct patterns from each other and the rest of the owl monkeys. My favorite example for a distinct throat pouch is Santa’s, he has a large white throat pouch that looks like a beard and makes him look like Santa Clause (which is why he was probably named this, I haven’t asked yet).

 These are all characteristics that are easy to see at night and can be spotted in an instant whenever the monkeys are not jumping around at incredible speeds, you could be following them intently with your flashlight thinking that you will never lose sight of them and with a quick motion they are gone and you are left searching all over for them and when you find a monkey if you can’t id them before they jump again your whole research may be fill with holes. This is more of a problem with the juveniles who are very active the adults tend to move with slower more calculated movements (unless they are in an enclosure with juveniles then they tend to get a little agitated as well). Once you have watched an enclosure enough times you can begin to identify the monkeys in it by their behavior. There are behaviors that can be peg to individual monkeys. Connie and Alled for example do backflips, Lucifer is always hooting lowly, spruce likes to hang from the roof in a unique manner (it looks like a v-shaped hammock) while her partner (dodge) has a designated spot under their box where you can always find him, Crunchy likes to walk hanging from the roof, and Betsy urine washes frequently. The lack of rapid movement can also be an identifying characteristic, as is the case for Rhetz since he is blind he moves very slowly.    

Using Camera Traps to Observe Owl Monkeys

Recently, we have been placing camera traps in the enclosures of several of our Owl Monkey families. There are many interesting behaviors and events that we can observe without actually being in the jungle. Every ten minutes, the camera traps shoot 30 seconds of video when a monkey passes in front of its motion sensor.  The benefits of using the camera traps to observe the monkey's behavior are quickly adding up. For example, four months ago we were able to capture video on the night of the birth of Connie and Gustavo's new baby! Here is a video clip from that night. Everything is in black and white because the camera traps use infrared cameras so as not to disturb the owl monkeys throughout the night.

You can see the infant with its parents here!

We have a camera trap set up in Connie and Gustavo's cage almost every night so that we can observe the growth and behavioral development of the infant. At this point, we have collected almost 20 hours of video observations, and have observed several developmental milestones such as the infant leaving the protection of its father and moving about on its own.

Meet Betsy: The 'World's Oldest' Owl Monkey

Betsy is in Pursuit of a New Partner!

A photo from 2004 of Betsy, her late partner Peanut, and their infant daughter Creamy. Picture courtesy of Dr. Christie Wolovich (c) 2004

This past week we began observing and collecting behavioral data on Betsy.  Betsy is a very special owl monkey because she not only is the oldest owl monkey at the DuMond Conservancy, but she is likely the oldest owl monkey in the world! She lost her mate Peanut last year and has continued living compatibly with her daughter, Crunchy.   Their companionship came to an abrupt and dramatic end about 3 weeks ago when she began fighting with Crunchy.  Owl monkeys live in family units, but once the offspring has reached maturity they will leave the group to find their own mate. Apparently, Betsy saw Crunchy as a threat to her territory and took matters into her own hands. Since then, Betsy’s rates of hooting (a vocalization that sounds like an owl hooting) and scent marking have increased tremendously. Owl monkeys rely heavily on chemical cues to communicate so we are trying to decipher her chemical messages. It seems that Betsy is ready for a new mate!

Introducing...Austin and Wookie's Baby Girl!

Every Tuesday, our team of researchers travels to the DuMond Conservancy to study the owl monkey colony at the DuMond Conservancy. Tonight was particularly interesting, as we discovered the sex of one of our new owl monkey infants. We are happy to announce that Wookie and Austin, two of our Aotus vociferans owl monkeys, are proud parents of a beautiful baby girl. The infant has yet to be named, so we are happy to receive suggestions in the comments box. We do not know very much about the behavioral and physiological development of infant owl monkeys. Wookie and Austin’s daughter is part of an ongoing study that hopes to shed light on the development of infant temperament. It was not an easy process to sex the infant.....

 Contrary to many species of new world primate, owl monkey infants are usually carried by the father until they can move about on their own. Photo courtesy of Christy Wolovich

Our veterinarian, Dr. Bob, had to enter Wookie and Austin’s home cage and capture the infant so that we could determine its sex and record its weight. Although the capture was a little stressful for the infant, we did not waste the opportunity to learn about its response to the stress. All vertebrate animals release stress hormones called glucocorticoids when they are stressed, and these hormones can be measured in blood, saliva, and urine. We collected urine from the infant before and after it was captured so that we could determine the levels of stress hormones that it had produced. Once we have collected urine from several of our infants at the Conservancy, we will compare their hormone levels to see if there are any differences between them. You will hear our results here first, so stay tuned to the team Aotus blog to keep updated on the happenings at the DuMond Conservancy’s research evening!