Howler Monkeys and Howlerween

Written by Kaitlyn Spross & Willam Weeks 

If you’ve been to the Houston Zoo primate section, you may have visited our awesome black howler monkeys:  Vida, Garcia and Ramone. And chances are they’ve either been asleep, resting in the sun or munching on leaves with what could be described as a ‘frowny’ look on their faces. Zoo guests often comment on our howlers’ pouty appearance. “Why does that howler monkey look that way? It looks so sad! Is that howler monkey judging me!?” The truth is, our howler monkeys aren’t sad at all! They just have on their resting howler face.

Howler 1.1When it comes to their diet, howler monkeys are mainly folivores, which means they eat lots of leaves and plant material. Because leaves are difficult to digest and don’t provide much energy, a howler monkey’s favorite pastime is taking a nice long nap to digest all that greenery. Along with their usual leafy foods, they do enjoy a nice fruit here and there as well. And, they even chow down on an egg once a week.

A howler monkey is at their happiest right after they have eaten; all they do is rest and relax while they absorb all that food. The Houston Zoo howler monkeys certainly live the life of luxury! They get their food delivered every day, and all they have to worry about it is finding the perfect sunny spot to take a six hour siesta.

When the howlers aren’t napping, they can be seen climbing around using their super-cool prehensile tails. A prehensile tail means that their tails are muscular and can be used to grasp things, like branches, which makes them particularly good climbers. Having a prehensile tail is like having an extra limb!

Howler 1.2If you come to the zoo early in the morning, you might even get lucky enough to hear our howlers monkeys howl! Their vocalization sounds like a very low, loud, and rumbling call that can be heard up to 3 miles away! It is a territorial call and also one which encourages the group to bond together as they vocalize.

This October, plan a visit to Zoo Boo Presented by Bank of America and our Howlerween conservation event each weekend.  You can visit our wonderful howler monkeys and learn more about what the Houston Zoo is doing to save howler monkeys in their wild habitat in Belize!

The Houston Zoo Helps Howler Monkeys in Belize

This post was written by primate keeper, Meredith Ross.

Wildtrack’s volunteers carry the howler monkeys through the jungle to the release site(photo courtesy of Molly Davis)

Belize is home to two species of endangered primates, the Yucatan black howler monkey and the Geoffroy’s spider monkey.  It is illegal to own primates in Belize, but despite that, one of the biggest threats in the wild is the pet trade. That’s where Wildtracks comes in. Located just outside Sarteneja, Belize, Wildtracks is home to forty-three monkeys, most of which have been rescued from the illegal pet trade. Wildtracks will rehabilitate these monkeys and release them back into the wild in the nearby Fireburn Reserve. Seventeen howler monkeys have been released into Fireburn thus far, and in June 2014, they were joined by four more. Two pairs of howler monkeys, “Sultan & Livvy” and “Paz & Kofi”, were placed in carriers, taken for a car ride, a boat ride and then were carried on bamboo poles up to their new home in the jungle. They were kept in pre-release cages for three days in order to acclimate them to their surroundings and then, on the morning of June 16th, their cages were finally opened and they were returned to the wild. Sultan and Livvy were the first to be released. Livvy began to explore immediately, while Sultan was a bit unsure, staying on top of the cage for a few minutes. Eventually they both began to move through the trees and happily munch on the plentiful leaves in their new home. Paz and Kofi were released at a site several yards away from the first group. Once again the female of the group, Kofi, was the brave one; she immediately started to explore her new jungle home. Paz had to be coaxed out of the cage by one of his caregivers, but then happily joined his mate Kofi, up in the trees. They will be followed by staff and volunteers for the next three months to ensure that they are adjusting well to life in the jungle. I followed Paz & Kofi for their first three days of freedom. They seemed a bit hungry on the first day, but by day two they were eating lots of leaves, finding nice places to rest near each other, and spending time at the tops of trees sunning themselves. Paz in particular is a success story. He spent his early life as a pet on a very short chain, where he could only rock himself for comfort. Even at Wildtracks, he exhibited nervous tics attributed to his former life as a pet. Once he returned to the wild, all those aberrant behaviors seemed to fade away as he followed his mate Kofi through the jungle.

Paz and Kofi exploring their new home
Kofi “hanging out” in the jungle
Photo courtesy of Wildtracks
Photo courtesy of Wildtracks


Back at Wildtracks, volunteers work tirelessly to prepare the next generation of monkeys for release.  The youngest members,” Ini” and “Vicki”, are at least three  years from release but they are still learning valuable skills to help return them to the wild, like which leaves to eat, and how to  climb branches that will support their weight. Like most of the monkeys at Wildtracks, Vicki was stolen away from her family and sold into the pet trade; she was moved to Wildtracks after being rescued by the Belize Forestry Department. Ini was found alone in the forest with a broken arm, his mother presumably shot by poachers. Despite their troubled past, both are doing great now, healthy and happy in their new home.

The Houston Zoo Primate Department has helped fundraise for Wildtracks and spread their conservation message for the last few years at our Howlerween event each October. Houston Zoo Primate Keepers have traveled to Wildtracks for the past couple of years to share their knowledge of primate care, including the creation of enrichment devices like the forage board above, as well as tracking the post-release howler monkeys in the jungle. In 2011, Houston Zoo Primate Keeper Rachel met a tiny, scared and malnourished 5 month old howler monkey named Nicky during her two week stay at Wildtracks. Last year, primate keeper Lucy Dee was there as Nicky was released back into the wild. This year, as I walked through the Belizean jungle, I got to meet Nicky. He was high up in the canopy of a tree, howling at the people below him, while the other members of his group kept traveling through the forest.  He is finally back where he belongs, successfully living as a truly wild howler monkey and a living testament to the amazing rehabilitation work of Wildtracks.

7We hope to continue to spread awareness of the importance of primates living in nature in order to finally stop the traffic of these animals as pets. Wildtracks and the Houston Zoo, working together, are making a difference in Belize. Come to our Howlerween celebration to learn more and see how YOU can help! To learn more visit

Photos courtesy of Wildtracks

Releasing Howler Monkeys in Belize – Rescued Pets Go Back to the Wild

Written by Primate Keeper Lucy Dee Anderson

In Belize it is illegal to own a pet howler monkey, and the forestry department confiscates monkeys from people to eventually be brought back into the wild. In June I had the opportunity to travel to Belize and help release two troops of howler monkeys back into a safe spot deep within the Amazon rainforest called Fireburn. (Wondering why they are not allowed as pets? Read all about why having a monkey as a pet is bad for the monkey and for you.)

Ritchie the howler monkey. Photo by Ruth Linton.

In Belize is ‘Wildtracks’, a non-profit organization that shelters the howler monkeys and rehabilitates them. This can involve medical needs, special feedings and/or socialization with other howler monkeys. Wildtracks receives animals aged from a few months old to adulthood. Each animal is eventually put into a group with other monkeys and once they become a cohesive group, they are ready to move on to the next step. This next step is the pre-release area, which is an area of forest fenced off by electrical fencing.

At Wildtracks, they have two pre-release areas, and they had two troops of monkeys to release this year. Nicky, Sultan, Livvy, Willow and Hazel had been living with Wildtracks for a year. The other troop, Charlie, Paz, Mia, Fern and Ritchie, had been at Wildtracks for about half a year. I was able to help them with this year’s release at Fireburn, an area of protected forest that traditionally had howler monkeys in it; therefore a great place to do a release! So…picture it; a bumpy ride on the back of a truck on a dirt road, then a beautiful boat ride across a lagoon, then a tractor ride deep into the jungle, then an hour trek even deeper into the jungle – this is how you travel to Fireburn Reserve!

Igor the howler monkey. Photo by Ruth Linton.

When we went to the reserve, there were several steps to accomplish in order to free a monkey:

1. Go to Fireburn and build release caging – this involved bringing a generator, drill, ladder and several panels of caging deep into the jungle!  This will be the monkeys’ home for a couple of days and also a home base once they are released.

2. Next we bring the monkeys to the jungle and put them in their release cages.

3. Allow the monkeys to get used to their surroundings, while feeding them fruit and  freshly cut leaves from the forest, called browse.

4. Release the monkeys!

5. Monitor the monkeys to make sure they are doing well and eating well. They will be provisioned with food for about 3 months until they start to eat on their own.

This was my second trip to Belize. I was there three years ago to meet some monkeys that were being rehabilitated and assist with the project. When we released the first troop of monkeys this year, that first group that I met three years ago came to see what was happening! It was so rewarding to be able to see the monkeys I met before being wild and free in the jungle again. One of those monkeys’ names was Eden. She had been confiscated as a baby, so small she could fit in your hands. When I first met her she was still being bottle-fed and was very wary of newcomers. It broke my heart to think that she had been taken away from her mom in the forest and was someone’s pet. When I saw her this year she was huge! As a fully grown adult at this point, she was swinging in the trees, howling and fully a part of her new troop. This gives me a good feeling that the 2 troops we released this year have a very good chance of thriving in the jungle of Belize!

Rehabilitation and release of any animal is a difficult and time consuming process. Although everything went extremely well overall, there were three monkeys that will need to wait until next year to be released. Livvy unfortunately broke her arm a day before the release and has had extensive medical care that is ongoing. Paz lost the rest of his troop and could not find them and so had to be returned to Wildtracks to try again next year, and Sultan, who was showing great movement and independence in the trees at Wildtracks, was simply not ready to be out in the wild and will also be tried again next year. Although these are setbacks, looking at the big picture, seven howler monkeys were successfully released this year!

My trip was made possible through the support of the Houston Zoo Staff Conservation Fund. The Fund is the donations of many Zoo employees, pooled together to support a select few of our staff’s proposals. It allows us to actively participate in conservation at many different levels and in places from Texas to far-flung areas like Belize. In the primate department, for the past 4 years we have raised awareness and provided funding for howler monkey conservation each October during our event called ‘Howlerween’. In addition to contributing funds, we travel to Belize and help them with whatever they need, from carpentry to assisting with medical procedures.

Thanks to this Fund and Wildtracks, I was able to contribute to conservation and have an amazing learning experience this past June!

The howler monkeys we have here at the Houston Zoo are ambassadors for the monkeys in the wild, and I hope to see all of you come to the Houston Zoo to see our amazing howler monkeys in action!

You Gotta Belize, it is Wonderful! By Primate Supervisor, Dena Strange

Did my title catch your attention? Now that my mosquito, spider, army ant and a couple of unidentified bites are healing up, I thought I should tell everyone about my trip to Belize that was sponsored by the Houston Zoo’s Staff Conservation Fund (donations from Houston Zoo staff  designated for Houston Zoo staff conservation efforts) .

I went down to visit Wildtracks , originally a Manatee rescue/ rehabilitation and release center in Belize. They added the endangered Yucatan Black Howler Monkey in 2010 to their wildlife rehabilitation program and have a successful release program in the nearby Fireburn Forest Reserve. Wildtracks is run by Paul and Zoe Walker and assisted by a dozen or so wonderful volunteers (how to volunteer at Wildtracks link) from all over the globe. Wildtracks is located 2 miles west of the tiny village of Sarteneja in northern Belize (accessed by either 40 miles of dirt road or a 90 minute water taxi…guess which one I chose!).  


The primate department at the Houston Zoo has been supporting Yucatan Black Howler Monkey conservation in Belize for many years (read previous blogs here) and Wildtracks since 2010. Last October the primate department raised almost $4000 during the annual Zoo Boo weekends by selling items (some of it hand-made by staff) and raising awareness of howler monkeys and Wildtracks by creating “ Zoe the Zoo Keeper’s Adventure” .  Zoe the Zoo Keeper is a character primate staff created to help tell the story of wildlife conservation in Belize.  The money raised in October was used to build more caging to house confiscated howler monkeys and to buy fencing for the new pre-release area (an area that prepares them for the wild again) for howlers.


The main purpose of this trip was to discuss opportunities for conservation collaboration with Wildtracks and the Belizean Forestry Department and explore how the Houston Zoo’s staff might enhance Wildtrack’s progress with rehabilitating and releasing howlers back into the wild. Owning wildlife is illegal in Belize and now that Wildtracks has the facility to accept more howler monkeys, the Belize Forestry Department has stepped up confiscations. However, most Belizeans are completely unaware that owning wildlife including howler monkeys is illegal. After meeting with Rasheda Garcia (Forestry Dept manager) and Paul Walker, we all agreed that the next step is focusing on educating Belizeans. We brainstormed several ideas and have come up with a plan that we hope to fulfill in the coming year!


You can learn more and help support Wildtracks by visiting their website (here) and/or visiting our table during Zoo Boo in October 2013. Mark your calendars and look out for Zoe the Zookeeper!


The monkeys I got to know in Belize By Primate keeper, Rachel Vass

Primate keeper, Rachel Vass got to go to Belize to assist in the rehabilitation and reintroduction of primates from the area.


“The three animals I spent the most time with were Nicky, Zultan, and Duma.  Nicky, is also a Howler monkey, is approximately 5 months old; he was confiscated by the forestry department of Belize and Wildtracks and came to live at Wildtracks on June 6th, less than a week before I arrived!  A resident in the local village heard him crying from inside a box on the back of a bicycle and contacted the authorities; he was confiscated and taken to Wildtracks to start the rehab and release process.  Unfortunately, when police officers went back to arrest the man who was previously in possession of Nicky, he had run away and was not found.  When Nicky arrived at Wildtracks he was extremely dehydrated and emaciated; needless to say he was terrified of people and was completely untrusting of anyone who went near him.  However, in just a few short weeks he has made dramatic improvements!  He is accepting many kinds of food types very well and is looking much more healthy and happy overall.  He receives small amounts of fruit daily along with a variety of browse (leaves and branches- fig is his favorite) as well as supplemental milk feedings every three to four hours throughout the day.  He is beginning to relax and get to know those of us who worked with him the most and will occasionally play a bit also.  He is still working on his climbing skills and building up muscle, of which he essentially had none, so that he can jump around and really be a “real” monkey!  He is still in his quarantine period so he can not have access to other monkeys yet, but as soon as his time is up he will be joining Sultan as a companion.


Sultan is another Howler who is approximately 8 months old; he was being kept as a pet by a family in Belize and was surrendered to Wildtracks in February, when they learned it was illegal to own a primate as a pet.  He is on the same feeding schedule as Nicky, and is receiving fruit and browse a couple of times a day and milk feedings every three to four hours.  Being used to people has given him a much more trusting attitude and caregivers actually play with him, hold him, and carry him around on their bodies acting as a surrogate mother.  While he still sleeps inside at night, he is much more physically developed than Nicky, and spends a lot of time outside during the day climbing in trees and leaping off of them onto our heads!  He is playful and rowdy with a very confidant “in-your-face” personality.


Duma is a Spider monkey who is approximately 18 months old who also came to Wildtracks in February of this year.  She was previously owned by a family in the nearby village of Sarteneja and was surrendered after she started to mature and became too active and dangerous for the family to handle.  Like Zultan, she is very attached to people since she was a pet for most of her infant life and needs lots of attention throughout the day; she also receives fruit and browse daily as well as supplemental milk three to four times a day.  There are plans for another 2 or 3 Spider monkeys to arrive at Wildtracks in the near future and she will be grouped with them once they finish their quarantine periods.”

By primate keeper, Rachel Vass

Rachel and primate keeper, Helen Boostrom enjoyed their time at Wildtracks immensely.  To read more about their work click here or scroll down.  Their experience was made possible by the Houston Zoo Staff Conservation Fund.

I got to work with Howler Monkeys in Belize! By Primate Keeper, Rachel Vass

The Houston Zoo’s Primate keepers, Rachel Voss  and Helen Boostrom recieved funds from  the Houston Zoo Staff Conservation Fund to go to Belize to participate in conservation research at a rehabilitation facility called Wildtracks.

The Wildtracks wildlife rehabilitation center is located in the north east corner of Belize outside Sarteneja on the shore of the Corozal Bay.  This is the same region where the care, rehabilitation, and pre-release of the black howler monkeys is occurring; the final release site for the howler monkeys is slightly to the southeast in the Fireburn Reserve, which is managed by Wildtracks.  Black howler monkeys have not been living wild in this area since the 1940’s (personal communication. Paul Walker, Wildtracks); although they have not recently been native to the northern part of Belize, they did historically inhabit this area, and chances for successful rehabilitation and release in this region are very promising.  


The following is the beginning of Rachel’s experience at Wildtracks.

 “When I was in Belize I spent most of my time at the Wildtracks headquarters doing a lot of animal care and other husbandry based tasks with the animals they have there (ie: socializing the monkeys, cleaning, feeding them, making enrichment, propping enclosures, and building new enclosures).  They have a total of 9 primates at Wildtracks right now, 8 Black Howler Monkeys and 1 Black Handed Spider Monkey.  Dudley, a 5 year old Howler monkey (who was supposed to be released with the group Helen blogged about- Agatha, Bonnie, and Clyde), broke his leg while in the pre-release enclosure and had to be kept back at headquarters until he healed completely.  He is well on his way to being back to 100% and will hopefully be moving back into the pre-release area within the next couple of weeks; he is moving around wonderfully and has healed quicker and beyond what anyone thought he would, you can hardly tell anything ever happened to him!  There are two other groups of Howlers that are in the rehabilitation process and will be the next to move to the pre-release area;  Minnie and Moe (two females) both around a year old and Eden, Kofi, and Igor (two females and a male) who are all around 18 months old.”   – Primate keeper, Rachel Vass

Stay tuned for more of Rachel’s adventures in blogs to come!  To read about Helen’s adventures at Wildtracks click here or scroll down.

The Howlers are throwing things at me while I watch them in the rain forest in Belize, By Primate Keeper, Helen Boostrom

Looking up at the howlers in a tree

This post is written by Houston Zoo primate keeper, Helen Boostrom, who is in Belize right now.  She is being supported by the staff conservation fund to do field work with Howler Monkeys in Belize.  Please go here to learn more about the staff conservation fund.  We will post these updates of Helen’s work as we get them, so stay tuned!

The howlers are tracked throughout the day and their movements are marked using a GPS so the process of their territory establishment can be recorded. This is sometimes difficult as the forest is quite dense and the howlers are adept at moving quickly through the trees. It is also really hard to spot them when they are high up in the canopy. If they are resting, you can walk right under them and not even know they are there. When the howlers travel, there is always the telltale sound of fruits and branches falling. A lot of the time on your head as you walk underneath them!

While keeping a close eye on the howlers high-up in the trees it is also important to watch the forest floor for snakes, such as the venomous fer de lance, poisonous plants like the poison wood, and various tripping hazards like vines and holes. 

venomous snake, the fer de lance

If that wasn’t enough to keep an eye out for, you must also record their behaviors as well as the plants they eat, including the specific type of tree as well as whether they are eating the fruit, the mature leaves, or the new leaves. This is the hardest part in my opinion. I spent the first few days just trying to learn how to correctly identify the plants found in the forests. Then just when you think you have it down, you realize that a lot of the trees have vines wrapped among the branches and even though they are sitting in the tree eating leaves it is the leaves of the vine and not the tree.

All of the information gathered from the study of these howlers in post release will help out in future releases of rehabilitated howler monkeys confiscated from the illegal pet trade. It will be used to assess future release areas in terms of the known food plants found in potential areas, the available space for establishing territories, and the availability of plants suitable for travel or rest. The information will also be used to improve rehabilitation protocols to increase the number of potential food plants the howlers are exposed to in the rehabilitation process and to better mimic the environment the howlers will experience in the forests, such as thin bendable branches and vines, throughout the rehabilitation process.

Keep checking back for more from Helen in Belize.  If you want to read her previous posts scroll down or go here.

Watching reintroduced Howler Monkeys in Belize, by Primate Keeper, Helen Boostrom

Howler looking down at Helen

This post is written by Houston Zoo primate keeper, Helen Boostrom, who is in Belize right now.  She is being supported by the staff conservation fund to do field work with Howler Monkeys in Belize.  Please go here to learn more about the staff conservation fund.  We will post these updates of Helen’s work as we get them, so stay tuned!

The day starts with a trip to the uppermost part of the rain forest canopy. Since it is the beginning of the rainy season in Belize, most nights have a few showers. The howlers are still in the process of figuring out which trees provide the most cover from the rain and so are a little damp. Lying on a high branch in the sun provides some warmth and a chance to dry out. While there they may grab a few leaves or fruits to snack on, but once they have dried out the real foraging begins. The howlers will spend most of the day alternating between foraging for leaves and fruit and exploring their new environment. When moving on familiar paths the howlers are quite confident and move easily through the trees. When they embark on an exploration of a new area of the forest they tend to pick their way through the trees carefully. It is important that they stay fairly high up in the branches as they are more likely to run into predators the lower they venture. It is also important to avoid rotten branches or ones that will not support their weight to prevent a long fall to the forest floor. An important part of the rehabilitation process for primates confiscated from the illegal pet trade like Agatha, Bonnie, and Clyde is that they learn these vital skills before they are released back into the wild.

The day of exploration is broken up by either one long nap in the middle of the day or two shorter naps, one mid-morning and one mid-afternoon. There are also several opportunities for play throughout day. Playing with another howler monkey is always fun, but if no one else is in the mood swinging by your tails and playing with nearby branches and vines will have to do. As the light begins to fade signaling the end of the day, the howlers find a sturdy place to sleep. Their current favorite resting place is in the center of a palm tree. All three can find a secure, sturdy place to sleep there and the giant leaves offer some protection from the weather.

To read previous post of Helen’s work in Belize go here or scroll down.  And stay tuned for more exciting stories straight from Belize!

Houston Zoo Primate Keeper Doing Howler Monkey Field Work in Belize

This post is written by Houston Zoo primate keeper, Helen Boostrom, who is in Belize right now.  She is being supported by the staff conservation fund to do field work with Howler Monkeys in Belize.  Please go here to learn more about the staff conservation fund.  We will post these updates of Helen’s work as we get them, so stay tuned!

Meet Agatha, Bonnie, and Clyde. Three endangered black howler monkeys that have been rehabilitated and released back into the wild after having been confiscated from the pet trade. Black howler monkeys can be found in parts of Belize and Mexico but are becoming more rare. A major problem is the illegal pet trade which takes baby howlers from their mother often resulting in her injury or death. These howlers are then kept alone in small cages with little opportunity to climb and socialize with other howlers as well as being given diets lacking in the leaves that they would normally consume in the forest.

Primate keepers from the Houston Zoo are currently in Belize helping observe these howler monkey at the fireburn reserve where they have been released. The howlers behavior, food sources, and movement are being tracked to monitor their progress adapting to life in the forest. This information can then be used to modify current rehabilitation protocols to increase the success of the program. Keepers are working with Wildtracks which manages the howler rehabilitation and release program in cooperation with the belizean government.

Please stay tuned for more from Primate keeper, Helen Boostrom.

The Wildlife Care Center of Belize

Black Howler

The black howler (Alouatta pigra) monkey of Belize, Guatemala and Mexico is an endangered species under the IUCN Red List.  One of the top three threats to this species includes the illegal trade in pets which results as a by-product of hunting for sale of bush meat in local and international markets.  The confiscation of black howler monkeys from the pet trade is overwhelming the Belize Forest Department and the Belize Zoo.  As a viable alternative to leaving monkeys with their owners, confiscated pet black howler monkeys are transferred to the non-profit organization called the Wildlife Care Center of Belize (WCCB) directed by Robin Brockett.  WCCB rehabilitates these pets and reintroduces them into the wild.  Over the past ten years the center has released 28 howler monkeys into the Monkey Bay National Park and Monkey Bay Wildlife Sanctuary.

The Houston Zoo Primate Department is helping to raise awareness about the WCCB and the illegal pet trade.  We are holding our 2nd annual “Howlerween” Spotlight on Species event on October 23rd and 24th.  We will have educational activities, keeper chats, and also be selling a variety of merchandise to help raise money for the WCCB.  “Howlerween” will coincide with Zoo Boo and from 9 am to 3 pm on both days at the Wortham World of Primates.

Written by, primate keepers, Lucy Dee Anderson and Cheka

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