Monkey & Ape Weights: Our Need to Know

Annie-WeightZoos all over the world now regularly weigh animals under their care. How does one weigh a huge orangutan or a tiny tamarin? Well, training your critter to sit on a scale is the first part, and patience is the second part. Oh, and a nice treat as a reward is the last (and best part) as far as our subjects are concerned.

Why do you suppose we need weights, anyway? Well, non-human primates have the same tendency as human primates do to gain excess weight and develop chronic diseases as a result. And, geriatric animals tend to drop weight – making sure that we are on top of weight loss is very important. In addition, medication dosages are based on body weight, so to be sure that our animals are getting a correct dose is vital.

Rudi gets weighed sitting atop his bench.

We have scales that are specially built to weigh the smallest to the largest animal in the zoo. Our orangutans have a special platform built on top of their scale that they sit on so that all body parts stay on the scale: when you have long arms, they need to be on the scale and not on the floor to get a proper weight. So, Rudi (pictured) is sitting on that bench on top of the scale. He and all of the other orangutans receive juice for sitting on that bench long enough for the keeper to read the weight, which is in “the brains” of the scale sitting outside the mesh. His current weight is 121 kilos, which is 266 pounds. This weight is recorded in our daily documentation which goes to the veterinary clinic for review.

Roberto getting weighed.
Roberto getting weighed.

Roberto is the Pied tamarin in the next photo, and he is one of our older fellows who we need to weigh frequently to be sure he doesn’t lose too many grams in any given week. He is trained to sit inside a small nestbox which is perched atop a gram scale. You’ll notice he is sticking his tongue out at his keeper…this is a tamarin insult and his equivalent of saying “I am the boss of you!” in monkey language. Once the treat of a fat, juicy wax worm was delivered, he stopped tongue flicking and swallowed his delicious prize. If he did lose weight, primate managers could propose a diet increase to bump him up again.

Weighing our animals is just one small part of excellent husbandry that takes place at the Houston Zoo, and our keepers take pride in making sure this is done regularly – and they always make it fun for monkeys and apes.

A Baby Mandrill Is Only Part of Our Primate Baby Boom

November has been a big month for the primate team at the Houston Zoo. Three brand new babies were born during the course of one month, including a rare mandrill.  At 2 a.m. on November 29 the hugely pregnant mandrill Louise delivered a baby. Mandrills are known for their striking facial features including blue-colored ridges on the sides of their muzzles and a brilliant red stripe down the middle. The gender of the new baby is still unknown, but the prominent muzzle ridges can already be seen. Louise has fully embraced motherhood, and has carried and nursed her new baby like a pro. Guests can watch Louise cuddling and caring for her new baby at Wortham World of Primates.

On November 1 a De Brazza’s monkey was born to Amelia who had just given birth to her first baby, Ruby, in January.  The little one is stunningly gold colored and is already beginning to get off mom and explore the yard. The expanding family lives at the Wortham World of Primates and can be seen daily in their lushly planted exhibit.


A pair of Goeldi’s monkeys that had not been successful in the past gave birth to a new baby on November 10. Peach, a young female, bred immediately with Andy, a more mature male, but sadly, their first baby was stillborn. The second time they conceived, the pregnancy ended in a Cesarean section, and again, that infant did not survive. The veterinarian team gave Peach a “time out” with a contraceptive implant, to give her plenty of time to heal and recover from both those ordeals. After a year, that implant was removed and she was healthy enough to try again. Lo and behold, with very little fanfare, a comparatively large baby was discovered on Peach’s back on November 10. Goeldi’s monkeys are different from the closely-related tamarins, because they usually have just one baby at a time, and the mom carries it for a month before dad joins in to help. The jet black infant is hard to distinguish on the parent’s back but a tiny face can be discerned in amongst the fur.

Cheyenne’s Story: What Happens When a Zoo Animal Gets Sick?

The Houston Zoo is very lucky to have a great veterinary team: a Director, a Manager, 4 Veterinarians, 3 Veterinary Technicians, and a myriad of other important players like zookeepers, purchasing and record-keeping staff. It takes a village to keep our animals healthy! Because of our continued, professional veterinary care at the zoo, the clinic staff’s daily schedule involves  routine health checks and monitoring newborn, chronically ill or geriatric animals. But what happens when an animal becomes acutely ill and needs veterinary attention? And, what special considerations needs to be made to treat an animal as large as an orangutan?
Cheyenne & Vascular Team 6.14

Recently, one of our most beloved animals fell very suddenly ill: Cheyenne, our 42 year old orangutan who has been a devoted mother to four adopted kids. She quite abruptly started refusing food, and more alarmingly, water, and all she wanted to do was lie in her nest. Her most recent adoptee, 3 year old Aurora, was happy and active and thankfully did not seem too worried about her mama, but her keepers and the vet staff were extremely concerned.  So, an action plan was developed and Cheyenne was sedated for a thorough physical exam. Indah, our 10 year old Sumatran orangutan female was selected to babysit Aurora while Cheyenne was away, as the two of them had a mutually friendly relationship already.


Cheyenne’s blood values were not looking good as her kidney function seemed compromised and several other important numbers were severely out of whack. Any number of problems could have been the reason for these aberrant results, and after consulting with a number of human doctors it was decided to do an exploratory abdominal surgery in case she had appendicitis or an internal abscess. Fortunately, neither of these were the case, so she was closed up and other veterinary specialists were consulted. It became obvious that she would need extended supportive care, which for an orangutan is not an easy task. A neonatal team of infusion specialists were called in to put an IV into a vein in Cheyenne’s foot, where she would be less likely to try to pull it out. It was covered by a cast once they successfully got it in, and she was kept partially sedated for her treatment and monitoring period that lasted two weeks. Through this IV lifeline, she received antibiotics, fluids and the sedative that kept her from being too active, while ensconced in a lovingly cushioned bed inside a recovery cage in the orangutan night house. She was watched carefully by the primate staff, who took turns staying overnight with her to make sure that her IV line was running properly and that she was resting comfortably. Keepers would offer her pureed fruits and vegetables via a long-handled spoon, and “milkshake” concoctions with everything from vanilla soy-milk to exotic juices, which she drank through a straw. Every 3 days, she was sedated more fully so that she could have additional blood tests done to check to see if her kidney values were improving.  At this time, her recovery cage was completely cleaned and she was given new bedding of soft hay, blankets and makeshift pillows. It was a long, drawn-out period where all of the staff who loves her rallied around her and did everything possible to maximize her recovery and comfort. And….it worked!

Cheyenne has been off the IV and back in with Aurora for a few weeks now, and is slowly but surely getting her strength back. She began going outside again after a couple of weeks, but only in the early mornings when the heat is not too intense. We feel so grateful for her progress and Aurora is very happy to be back with her mama again.

We can never predict when one of our treasured zoo animals might become ill, but when it happens, there is no more determined set of people than our veterinarians and keepers who try their best to make that animal well again. And, we are very lucky to have them.

Baby De Brazza’s Monkey Makes First Appearance!

New baby
New baby!

There are 91 De Brazza’s Monkeys at 31 zoos in the North American Species Survival Plan (SSP) managed population. Of all those, we believe we have one of the cutest individuals, in the form of the baby that was born on the last day of 2013. It has been fascinating to watch this kid’s development and coloration changes. Rupert …or Ruby… has gone from an astonishing brilliant golden color to the nearly adult pelage of the parents in the past six months. On those two names: we haven’t been positively able to see if the baby is male or female so we are leaving the question open until we are sure. (Whenever we get close enough to get a good look, the baby jumps into mom’s arms and she runs off, making a closer inspection impossible.) So, Rupert or Ruby it is until we get a look or we do the baby’s first physical exam, which usually occurs sometime around a baby turning one year old.

At 4 months on prop JPG
4 months of age

At six weeks of age a lovely white beard and mustache appeared on the infant’s face, but the golden color of the fur remained. We began to see the baby getting off mom and tottering around for small jaunts at this stage. At seven weeks of age the infant started eating kale and peas, which were picked up very delicately with tiny fingers and chewed contemplatively.  At eight weeks we documented the face getting somewhat darker, and at nine weeks he or she really starting to locomote around with much more confidence. At four months old baby was clinging to mama much less and climbing around and had graduated to eating lots more solid food. By five months, the facial coloration of an adult De Brazza’s monkey but the body fur was now a rust color.



At 6 months
6 month photo

Now, at the age of six months, the baby has developed into a mini-me of his mother and father and is very independent and starting to behave like a typical baby monkey, with all of the hijinks that go along with that: climbing, hanging upside down, swinging with great abandon, and generally just having fun.

Ruby being groomed by mom. Photo credit Tyler Kirchoff
Ruby being groomed by mom. Photo credit Tyler Kirchoff

This trio can be seen at the Wortham World of Primates in a newly renovated exhibit: go just past the patas monkeys and mandrills up on the elevated walkway and you will find them. They have a thickly planted exhibit so they may be a challenge to find at first, but have patience and wait – you will be rewarded with the sight of a beautiful new baby and a proud set of parents!

Orangutan Transfers: Why and How?

One of our orangutans, 10 year old “Solaris”, recently moved from the Houston Zoo to the Virginia Zoo in Norfolk, Virginia. This move took a lot of coordination between our two institutions, as well as cooperation between our Keeper staff and the orangutans.

Solaris and Dara bonding

Orangutans have the longest period of dependency on their mother of any primate, staying with mom for 8-9 years or longer. This bond is a naturally strong one, but when it is time for the kid to move out and away from mama, she lets them know in a firm way. In nature, she might gradually encourage independence of her offspring, or she might start throwing sticks at him to make him leave to go and find his own territory. Here, Solaris nursed until he was 7 years old, which is perfectly normal, but we found that Solaris was sleeping in a separate night nest from mom Kelly by the time he reached 8 years. By 9 years, he had moved his night nest into the adjoining room from her, as if instinctively knowing that it was getting to be time to move on.

We used those cues to begin doing both separation training and crate training. There is a ton of preparation that goes on prior to a move of any of our animals, but most particularly with the great apes. Keepers began closing the door in between Kelly and Solaris’ rooms for a quick second to start out with and then moved to longer intervals, rewarding both of them for allowing the door to be shut. The crate training began just as slowly and gradually: once the crate was attached to the door, Solaris had free access to it and it became a place for him to play. Over a 2 year period, we very slowly closed one of the doors so that he became used to being inside with a small gap to go in and out of. And, we made the crate a fun place by adding substrates, ropes to swing on, and of course he got treats when he went inside it.

Many guests ask the question: why do we send out our animal’s offspring when they grow up? The answer has to do with genetics. We do not want our animals to inbreed – they have very good systems of avoiding inbreeding in the wild, but here we have to help them. Matches that are genetically appropriate are made by the Species Survival Plan (SSP) and zoos all over the world carry them out by moving animals around. The orangutan SSP also looks at the behavior and personality of animals when they do their matchmaking, in addition to those all-important DNA traits.

Lynn blog 2
Solaris and Dara play outside

A keeper and a veterinarian from the Virginia Zoo came to the Houston Zoo three days prior to the shipment, so that they could get to know Solaris prior to his move. This is one of the important steps that most zoos like to take now to make sure that their animals don’t get too many surprises when they go off to a new home. Solaris was delighted by their company.

On May 1st, Solaris was calmly loaded into his crate, and we set off in a van to go to the airport. His main keeper Tammy went with him, and sat next to him in the truck as we headed off to the terminal. She was there nearby throughout the flight and then in the next van that drove him to the Virginia Zoo. She fed him various produce items, gave him drinks of water and juice, and handed him fabric that he would wrap around himself and play with during the trip. He always knew that someone familiar and friendly was with him during his travels.

When they arrived at his new facility, he was easily released from the crate and he began to explore his new digs. The Virginia keepers had set up a nice bedroom with places for him to swing, climb and rest. He could immediately see his new female friend “Dara” and within 3 days was introduced to her. They have bonded nicely and after passing their quarantine period are now going outside into a beautiful new outdoor enclosure which features tall sway-poles, hammocks and platforms, an expansive grassy area and a stream.
Lynn blog 1

Mom Kelly, in the meantime, is now acting more relaxed and playful than keepers have seen her in years, telling us that it really was time to “cut the cord” on this relationship. And, she has been reintroduced to adult male Rudi, whom she hasn’t visited with in twelve years. They have rekindled an old friendship which they’ve shared ever since the two of them were kids, and it was lovely to see them back together again. Come to the Wortham World of Primates to see this pair enjoying one another’s company once more!

Ring-Tailed Lemur Twins Starting to Venture Off of Mom

The ring-tailed lemur twins born on March 25th are growing up fast, and are even starting to get off mama and play with each other.

Ring-tailed Lemur-Babies-0051-9818

Play is a rehearsal for what they need to do in their adult life, so wrestling is for learning combat skills and running around after each other is good practice for avoiding predators. They still run back to mom after all that activity, however, and climb up on her back. Or, one will take the “jockey” position and the other will cling to her belly for nursing privileges.


Their two older brothers Howie and Finnegan are delighted with their new, tiny siblings, and occasionally try to run off with them when they do venture off. Mother Cairrean has an opinion about that, and chases them down and cuffs their ears as discipline for stealing her newest charges, before abruptly taking them back.


The twins still spend a lot of time perched on mama’s back, surveying the world from the safety of her fur. They startle at grackles, seem astounded at the Madagascar big-headed turtles when they move, and look to the protection of their mother when a Life Flight helicopter flies over their exhibit. Everything is new and interesting right now and they still have a lot to learn!

Check out this video and see if you can spot both babies. It’s not easy…

Great Apes: What's So Great About them, Anyway?

Gorillas, chimpanzees, bonobos and orangutans: these are the Great Apes. The lesser, or small apes are the gibbons, but let’s focus on the Great Apes right now. So, just what makes a gorilla different from a chimpanzee or bonobo or an orangutan?

Well, as it turns out, a lot! Perhaps it’s easier to talk about their similarities.

gorilla babyyThey are all highly intelligent and very closely related to humans. They all use tools, they all have complex thought processes, and they have emotions just as we do. They have a long gestation period to grow that big brain that all apes have. All ape babies stay with their mothers for a long time, because they all have long lifespans and there is a lot for them to learn before setting off on their own. And, did you know that all of the great apes laugh? During mutual play or when being tickled, all apes have a laugh similar to humans; just quieter.

Gorillas, chimpanzees and bonobos are the African apes, and they are behaviorally very different from one another. Gorillas are the largest and most formidable looking, but are quite peaceable most of the time. The males will use their considerable bulk to do chest-beating and bi-pedal displays that are both impressive and terrifying, which probably accounted for their fearsome reputation before scientists discovered how laid-back they really are. The males will fight with each other and will “discipline” a wayward female, but for the most part they are low-key and spend their time eating, relaxing and grooming each other.

Chimpanzees and bonobos share the scientific genus Pan but couldn’t be more different from one another. Chimpanzees are very social, but use aggression and war-like behavior as well as play and grooming to enforce their social codes. They have also been seen in hunting parties to capture and eat monkeys and small antelope: behavior seen only in humans prior to this discovery. Bonobos are also highly social, but instead use grooming and sex to express their convivial nature.

gorillazOrangutans, the only Asian ape, are completely different from all the other apes. They are semi-solitary, which defies comprehension when you get to see two of them playing together. They have high social abilities but they just don’t express them that often. Most of the time, males are solitary and females are alone until they give birth: then they are VERY social with that one infant, for a very long time. They will nurse that baby until it is 6 or 7 years old and that ultra-protected youngster will stay with mama until the age of 8, 9 or even 10! It is the longest period of dependence of any other primate infant.

The one thing that all of the Great Apes unfortunately have in common is that they are all highly endangered. The African apes are losing their habitat to coltan mining (coltan is found in all cellphones and is why everyone should recycle their phones instead of just discarding their old ones). And, orangutans are dying because of the palm oil crisis: the oil that allows products we eat and use to remain on shelves for a long time is palm oil. Plantations that take up miles of formerly pristine rainforest are eating up orangutan habitat by the minute. We can look for sustainable sources of palm oil in our grocery items to help.


A Blonde Baby is Born!

In the Primate department, we are rarely surprised by a new baby. However, on New Year’s Eve Day, a keeper came in to discover a breathtakingly beautiful new baby: a De Brazza’s guenon. The keeper, Lucy Dee, was so astonished that she almost couldn’t believe what she was seeing: a golden blonde infant clinging to the mother, “Amelia”.


Most infants born in the zoo are not surprises: we know when the breeding occurred, we know how long the gestation is, and we know about when to expect the new arrival. However, in this case, we were all completely gobsmacked. Once we recovered from the shock, celebrations began. All of us felt that this baby’s arrival was special in a number of ways. First, the parents were imported from the Democratic Republic of Congo in central Africa. It is highly unusual for zoos to have any wild-born primates anymore, as the days of zoos capturing mammals for exhibit has been long-gone for decades. The vast majority of primates are born in zoos and then traded within institutions to ensure genetic diversity – the Species Survival Plan decides where they should go to breed to keep the population healthy. However, this pair was confiscated after their discovery in an African bushmeat market, and shipped to the USA back in 2006. We very much hoped for offspring because descendants of wild De Brazza’s monkeys would be an important addition to the gene pool of this species in North America. Secondly, this species is not the most endangered African primate, but it is declining because of loss of valuable rain forest habitat and the bushmeat trade.

Breeding animals that are declining in the wild is one of our biggest and most important goals. But, no progeny was forthcoming for seven long years. Then, this past June, we needed additional space in our indoor facility because we were receiving a new group of mandrills, and the De Brazza’s pair shared the mandrill area. We are lucky to have a heated outdoor off-exhibit area available, so we decided to move them there while the extended mandrill introductions were ongoing. The guenons settled in to a routine nicely in their new home, and we turned our attention to mandrills.

Infant at one week
Photo credit: Lucy Dee Anderson

We may have been lulled into complacency after such a long time without a baby from this pair, so truly, it was an ecstatic staff that broadcast the news about this new infant to the rest of the team. Most of the crew had never even seen a De Brazza’s guenon baby before, and were amazed to see the blonde coloration. Adult De Brazza’s are some of the most stunning of the African monkeys, and this baby was no exception. Brilliant colors seem to be a hallmark of all the guenons and the infant lived up to what will be beautiful adult markings.

We were impressed with Amelia’s calm demeanor as she groomed and nurtured her new infant. She seemed completely at ease in her new role as a mother, and the sire, Albert, seemed quite protective of his expanded family.

The sire, Albert.

Now that they are ensconced in their cozy area and have been doing so well with the new young one, we have decided to leave them in place until the infant is older so as not to disturb them. We will keep everyone apprised about the baby’s growth and development until they do go back out onto exhibit. Sharing this lovely surprise with the world is an enjoyable if unexpected treat for us!



New Kid on the Block – Another Baby Sifaka Is Born!

On the 13th of December another infant Coquerel’s sifaka made his appearance. We knew that mama Zenobia was pregnant again, but this baby was born earlier than any of her previous kids. This is her fourth baby, and she is really a pro at mothering by now.  Protective and affectionate, she washes her baby enthusiastically and frequently and spends time examining all his limbs, fingers and toes as if fascinated.


New mama and infant outside for the first time since birth - photo by Stephanie Adams
New mama and infant outside for the first time since birth – photo by Stephanie Adams

As with all baby sifakas, we weighed the infant on the first day and he was a petite 92 grams (a tad over 3 ounces). He has gained on each successive weigh-in and two weeks later is a whopping 134 grams (4.7 ounces of fun!) The weighing is a necessity to make sure that these delicate infants gain properly – none of our other primate babies are ever removed from the mother for weighing unless they have a health problem.

Gulliver in hand after weighing - photo by Lucy Dee Anderson
Gulliver in hand after weighing – photo by Lucy Dee Anderson

The weighing process is a very quick one that Zenobia has become acclimated to. Keepers enter her enclosure and the infant is swiftly removed with a gloved hand. He is then put onto a small surrogate doll so that he can cling to it, and, once weighed, put straight back onto mama’s belly. Vets are there for the first few weigh-ins just to make sure all is well with the new wee one, christened “Gulliver”. So far, so good: we have a healthy baby that will make his appearance with his family soon, weather permitting, at the Wortham World of Primates!

How Our Primates Get Their Grub On

One of the most important duties that zookeepers have is to make sure that the animals in their care are engaging in “species-typical behavior.” This means that we want our animals to behave in the Zoo the same way they behave in nature. And, in nature, a good portion of a primate’s day is spent looking for food. Ripping up bark and leaves, searching for fruit, insects and gum exudates (a sap-like substance), as well as digging in the dirt for tubers or roots are all ways that primates can find food in the wild.

In the Zoo, primates do identical behaviors with their enrichment foods. We scatter sunflower seeds, peanuts or mixed nuts around their exhibit before releasing them from their night houses.


We take ketchup, mustard or relish and drizzle tiny bits of it in places where it will be a surprise when they find it. Sometimes a teaspoon of non-fat yogurt or low-fat peanut butter might be smeared on some branches here and there, to the delight of the monkeys who find it. All of these foods are spread out in unexpected places and found only after the primates have eaten their most nutritious foods of primate biscuits and leafy greens, which are served for breakfast.

Our Animal Nutrition department prepares all of these goodies, and also procures earthworms, waxworms, mealworms and crickets, all of which are part of a rounded primate diet. Although primates are mostly vegetarian, some will slurp up a nice fat earthworm without a moment of hesitation!

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