Creating "Webs" for the Spider Monkeys

August 19, 2019

By Ethan Riepl, Primate Keeper

The Saint Louis Zoo is home to three female black-handed spider monkeys: Jenny, Patty and Sammy. The most identifiable thing about spider monkeys, aside from the happy little noises they make when eating food, is arguably their impressive prehensile tails, which is a tail that can grasp and hold onto things.  A common misconception about primates is that they all have fully prehensile tails; however, only a handful of monkey species native to Central and South America possess this unique attribute,  including spider monkeys, which we have here at the Zoo. 

The tip of the tail is hairless and textured for gripping, rendering it almost as functional as their hands. Essentially they have a tail-version of fingerprints, complete with patterns unique to each individual.

While capable of picking up objects as small as a sunflower seed and occasionally being used to hold food when moving around, the tail often seems to have a mind of its own and is largely focused on searching for something to grab onto. Spider monkeys live in the highest level of the rainforest canopy and this prehensile tail gives them a safety line.

Visitors to the Primate House will likely notice the variety of complex feeders and toy-like objects in all primate habitats. These are common examples of the enrichment that is provided on a daily basis, specifically appealing to primates’ natural curiosity and problem-solving abilities; however, there’s a lot more going on when it comes to enrichment, both in plain view and behind the scenes. To start, environmental enrichment is all about providing opportunities for animals to engage in natural behaviors. While the aforementioned feeders and objects elicit some fairly conspicuous behaviors from the animals, such as foraging, problem-solving, investigation and manipulation of objects, they don’t represent anywhere near the full range of behaviors typical of most primate species. To identify and address those behaviors, keepers start by creating a detailed profile of each species concerning all aspects of their natural history. The questions range from the straightforward (What does it eat? Where does it sleep? How does it move around?) to a little more complex and obscure (How does it identify and communicate threats? Does it maintain a territory and, if so, how does it defend and utilize it?), and it’s not all that uncommon to encounter things that science just doesn’t know. This compilation of all available information about each species serves to paint a comprehensive picture of an animal’s lifestyle, the challenges it is equipped and expected to deal with, and ultimately its behavioral needs. With this information in hand, keepers regularly and repeatedly evaluate how well the current environment provides opportunities for the animals to engage in each of their respective behaviors. Wherever things are found lacking, keepers focus on creating those opportunities via new enrichment, perching and habitat decoration and even making adjustments to the daily management and routine. Environmental enrichment is a perpetual cycle of planning, implementing, evaluating and readjusting, and is always improving the standards of animal welfare.

A few years ago, the spider monkeys were the focus of this reevaluation process and the arboreal nature of the species was brought up.  Keepers do a great job of creating perches in the animals’ habitats and the spider monkeys were no exception; the habitat was a cobweb of ropes and branches and gave the animals ample opportunities to use their climbing abilities.  But there were a number of things that were brought up during the in-depth discussion: keepers could only hang food up to 7 feet off the ground; the animals were limited to the obvious pathways of the ropes and branches when getting around; many of the branches were more suited for walking across rather than hanging from; and aside from the attachment points in the ceiling that perching was suspended from, the very top of the habitat was severely underutilized. Spider monkeys are capable of supporting their entire body weight just from their tail, and keepers wanted a solution that strongly encouraged that behavior, in addition to addressing the other issues that were raised. Brainstorming ultimately led to the idea of creating a rainforest-like canopy in the habitat; a structure as high off the ground as possible, designed with hanging and swinging in mind and offering the animals the freedom of choice to move around it in whatever direction they pleased. Factoring in ease of construction, animal safety, and weight, the final design called for a massive cargo net that spanned the entirety of the habitat, built from seat belt material and pop rivets, and bolted to the ceiling. Constructing such a thing is no small feat, but fortunately there exists the Volunteer Enrichment Build Team, which meets monthly to tackle large, complicated, or intensive enrichment projects that keepers around the Zoo may not have the time or resources to do themselves. The volunteers were able to make quick work of it and it was soon ready to be installed by the Zoo Facilities Management crew, along with a system of pulleys that allows feeders to be raised up to the level of the canopy.

Now, these three spider monkeys are quite seasoned individuals and have had plenty of time in life to establish what they do and do not like.  One thing that has always held true for all of them is that they view new and novel things with significant skepticism, which can be a very useful natural behavior when it comes to encountering potentially dangerous situations. But as novelty is the spice of life and an important behavioral need to be addressed, keepers maintain a healthy regimen of new and unfamiliar things for all the animals and even for the spider monkeys, in spite of their staunch disapproval. So when the day finally came to introduce them to their newly decorated habitat, the old adage ‘You can lead a spider monkey to a cargo net, but you can’t make her climb on it’ never seemed more true. Cautiously entering the habitat huddled together for safety, they soon launched into a chorus of alarm barks and set about angrily shaking branches and ropes, as spider monkeys are known to do when they encounter someone or something they view as a threat. It took a full day for them to finally settle down, another two before anyone came close to approaching the cargo net, and almost two weeks before any of them got comfortable enough to actually hang from it.  They’ve since overcome all their fears and can now frequently be seen exhibiting all the natural behaviors of a canopy-dwelling primate, even deciding that it’s occasionally a nice place to grab an afternoon nap.

Click the photos before to see a larger image. Photos: Ethan Riepl

Global Tiger Day

July 29, 2019

The Carnivore Unit here at the Saint Louis Zoo cares for our Amur tigers, Kalista and Waldemere. Some of our duties to provide for these amazing animals include the obvious cleaning of their habitats and bedrooms as well as feeding an appropriate and healthy diet. But we have many more responsibilities.

We invest time in observing their behavior and condition. We investigate and implement an enrichment program that provides opportunities for them to demonstrate their natural behaviors (like putting scents in their habitats for them to investigate). We also help build voluntary trained behaviors that facilitate better care (like training the tigers to present certain body parts for inspection). We ensure they have comfortable places to rest (cats sleep a lot!), they have opportunities to play (they can be hard on their toys) and that we respect their capabilities as an apex predator (meaning they have no natural predators and are at the top of the food chain). We do all of this with the goal to increase their positive welfare.

It is an honor to care for and get to know these wonderful individual tigers, each with their own personality, and I am grateful each time I hear their distinct "chuff" vocalization to say "hello." - Julie Hartell-DeNardo, Zoological Manager of Carnivores 

Learn More About our Tigers

Happy Global Tiger Day! We are excited to celebrate this important day with our community, raising awareness for tiger conservation and sharing how we care for the Zoo's Amur tigers, Kalista and Waldemere. It is a privilege to be a part of their animal care team and get to know them individually. One of my favorite opportunities as a keeper is to watch them grow up and to care for them through all their life stages: as rambunctious youngsters, elegant adults and noble seniors. For example, Kalista was born at the Philadelphia Zoo in 2001, then two years later, she moved to the Saint Louis Zoo on a Tiger Species Survival Plan breeding recommendation. It was amazing to watch her mature into a stunning adult, meet her first mate and eventually become a very successful mother. We are committed to Kalista and Waldemere's specific, lifelong care to ensure enriching and comforting lives now and well into their golden years. - Carrie Felsher, Carnivore Keeper

Our Amur tigers Kalista and Waldemere are 18 years old and 16 years old, respectively. While we do have two tigers, you'll only see one tiger in the habitat at a time. While one tiger is in the habitat, the other is inside in the dedicated tiger bedrooms. The tigers' inside space is equipped with resting places, toys and an air conditioner/heater. The keepers work near there, too! The tigers can watch us work throughout the day and socialize with us while we are on the move. Tigers are a solitary species in the wild, and we try to replicate that here at the Zoo. We rotate our tigers twice a day so that they get equal opportunities to be outside. In general, one goes outside during the day, and the other goes outside overnight. We swap this schedule once a week as well so that both individuals experience the same amount of daytime/nighttime. This means that if you come to Big Cat Country in the morning, you will see one tiger, but if you come back at the end of the day, you might see the other one! - Jackie McGarrahan, Carnivore Keeper

In the Carnivore Unit, we regularly catch our tigers by the tail...well, sort of. Actually, Kalista and Waldemere allow us to safely handle their tails during training for blood draws. As our tigers are both older animals, it is advantageous to be able to regularly run bloodwork on them in order to monitor their health. Both tigers are trained to enter a training chute. In the chute, a tiger can eat their meat while Carnivore Unit trainers and/or veterinary staff can pull their tail safely through the side in order to access a vein to draw blood. This training is built on the basis of positive reinforcement training and operant conditioning. The tigers always choose to enter the chute, and they can choose to leave or remove their tail from the trainer's hands at any time. Fortunately, the tigers are always eager to participate in training sessions, and we are able to regularly practice this behavior. This is just one way we are able to provide the Saint Louis Zoo's tigers with the best possible care. - Carolyn Kelly, Carnivore Keeper

As a carnivore keeper here at the Saint Louis Zoo, I have an incredible opportunity to interact and work with an amazing species, the Amur tiger. Both of our tigers, Kalista and Waldemere (Waldo), have very different personalities. Kalista, our female tigress, is extremely engaged with keeper staff, very social with everyone she meets (even strangers) and she will greet most anyone with a tiger-specific vocalization called a "chuff" (greeting behavior). Waldo, on the other hand, is the big handsome male who tends to be more independent socially. He likes to do his own thing, and we keepers take on the challenge to create interesting enrichment that he will explore. One thing that really spikes his interest is our female tiger's scent that he immediately picks up the second he goes outside. Tigers will open their mouths wide, curl their lips back and show their teeth. This is performed over a site, scent or substance of particular interest to the animal, and this goes on for quite a few seconds. This behavior is known as the Flehmen response. So next time you see one of the tigers with their mouth wide open and showing their teeth, you know they have picked up a scent that has caught their interest. - Travis Shields, Carnivore Keeper

Amur tigers are one of 18 species (42 total individuals) that we get the privilege of caring for in the Carnivore Unit. Each individual animal has unique requirements, but there is one thing that we as keepers are always striving for—happy, healthy and active animals. One of a keeper's best tools in accomplishing this is the process of providing enrichment. Enrichment can be defined as any opportunity that improves or enhances the animals' environment within the context of their biology and natural history. This means that we are tasked with understanding the behavior and biology of each of our 42 animals and can tailor our enrichment programs off of that information. For instance, some of the biggest instinctual drivers for tigers include scent marking and stalking/ambushing. Through our enrichment program, we are able to provide a lot of different scents that the tigers are attracted to, such as hair and bedding from prey species, colognes and perfumes, and spices and herbs. We also provide large items that the tigers can stalk and attack, such as large barrels, boomer balls and burlap bags full of bedding. These items are often paired with a scent that attracts them. Seeing our animals interacting with enrichment opportunities that we provide them can be one of the most rewarding experiences as their caretakers. Animals showing a wide range of natural behaviors is a sign of good welfare, but it also gives visitors an opportunity to see our animals being who they truly are—wild animals. - Nate Aalund, Carnivore Keeper

Ask a Zookeeper

July 22, 2019

In honor of #NationalZookeeperWeek, we asked a few of our keepers some of their profession’s most-asked questions. A special thanks to Katie Stryker (Sea Lion Sound Keeper), Lindsey Gray (Jungle of the Apes Keeper), Mary Witucki (Carnivore Keeper), Clinton Scaggs (Penguin & Puffin Coast Keeper), Daniel Schneider (Carnivore Keeper), Glenn Frei (Invertebrate Keeper), Jackie McGarrahan (Carnivore Keeper), Maria Elden (Bird Keeper), Justin Elden (Herpetarium Keeper) and Carolyn Kelly (Carnivore Keeper) for taking the time to answer the questions. #ImAKeeper 


The Saint Louis Zoo receives many inquiries from kids and adults interested in learning what it takes to be a zookeeper. We also receive questions regarding careers in related fields, like wildlife management, forestry, conservation, and ecology. We're gratified that so many people like animals and want to work with them. And we're happy to help people understand how to prepare for a career in zoos, aquaria, and other wildlife organizations.

So You Want to be a Zookeeper?

Meet a Keeper

Keeper chats are offered every day at 10:30 a.m. and 2:30 p.m. and at 5:30 p.m. on Saturdays and Sundays in various locations throughout Zoo.

Meet a Keeper Schedule

National Zookeeper Week

Please join us in honoring this amazing group of animal specialists! Our zookeepers devote their lives to taking care of very special animals on a daily basis, to conserving species for the future and to educating the public about the need to preserve animals and their habitats.

July 21-27