When people find out I work for the San Diego Zoo, they almost always say, “How cool! You get to work with all the animals!” Well, yes… and no. As a horticulturist, I use my knowledge of plants to try to make the animals’ habitats enriching, fun, safe, and, more than anything else, a comfortable home.
BY Judy Bell
Photography by Ken Bohn
Creating a new exhibit from scratch or even remodeling an existing space takes teamwork. Through multiple meetings, horticulturists, arborists, keepers, behaviorists, architects, construction and maintenance staff, curators, and operations personnel work together toward a common goal: an excellent home for the animals. The questions in the design phase are many. What should the habitat look like? What does the animal need to thrive, physically and mentally? How can we foster the animal’s expression of natural behaviors? These questions help us define what “furniture” will be needed. Huge tree stumps, logs, large trees, shrubs, tall grasses, specialty plants, and more are supplied by the Horticulture Department.
Furniture for Fauna
Many of the Zoo’s exhibits have massive logs for the animals to climb on, over, and under. One way to get furniture like this is to have a big storm. Then we gather up any downed trees that fit the bill as candidates for placement inside an exhibit. The best trees to use are eucalyptus, because they have hard wood and many natural oils that make them water repellant and resistant to rot. Other tree species can be used, but they may have to be replaced in a matter of years, a costly aspect to “re-furnishing.” I used to feel a bit sad when a tree was felled, until I realized that no tree in the Zoo could have a better “afterlife” than to be a jungle gym for a young orangutan or gorilla. No tree, branch, or rootball is ever wasted here at the Zoo. Many of the original pieces of eucalyptus wood placed in the gorilla exhibit when it was built in 1991 are still there. They are considered “antique furniture” at this point!
Moving these pieces takes teamwork and the right kind of equipment. A crane lifts logs into a big truck for transport to a holding area and unloads them. Cranes come into play again when it’s time to place the furniture in an open-topped exhibit. If the exhibit has a roof or netted top, we also need a door, at least as wide as a Bobcat® (the tractor-type bobcat, not a feline). Sometimes we just use good ol’ muscle—and a lot of it!
Fit and Function
On occasion, an exhibit getting a “remodel” already has some plant material in it to work with. However, if there are large trees positioned close to the exhibit’s perimeter, we determine if they need to be relocated. Trees in such a spot may provide an avenue for escape as they grow—especially for arboreal primates. Such huge trees pose another problem in a closed exhibit if they press against the wire barrier. In either case, the Zoo’s tree crew uses their abundant skills to artistically “reduce” the canopy. And they continue to do so on a regular basis for the lifetime of the exhibit.
In addition to taking steps to ensure the trees don’t harm the exhibit structure, we also consider and plan for ways to protect the flora from the fauna. Barriers to guard trees from inquisitive and diligent chewing critters come in all shapes and sizes. Large rocks placed around the base of a tree are one way to prevent root damage from animals that like to dig. Wire mesh covering branches and tree trunks discourages chewing and bark removal that, if continuous, could eventually cause the death of the tree. These solutions work well with most hoofed species and small primates.
Creating naturalistic habitats for great apes provides a completely different challenge. By nature, they are in a constant state of “eating their environment,” and as a result, they need regular reminding that the landscape is not their lunch. This reminder is usually reinforced by a protective “hot wire,” which sends a mild electric pulse to discourage contact. The large trees will continue to provide shade as long as the protection is in place and the animals don’t figure out how to get around it. In the case of many primate exhibits, we use fake trees or metal armatures with rope hammocks for convenient and comfy places to hang out and relax. We have also created faux ficus trees by using cuttings of ficus rooted in manmade structures. These are placed within arm’s reach of the primates, so they can browse on the material at their convenience.
The overall selection and placement of plant material is critical to the ultimate success of an exhibit. A plant’s roots stand a much better chance of survival if they can be sheltered by a deadwood log or tucked away between rocks. If plants that are not typically used as browse are used as exhibit plantings, the inhabitants may not see them as edible and pass them by.
Regular replanting and reseeding of exhibits is a way of life for our horticulturists. By using a variety of grasses—clumping and running, warm season and cool season—there will always be something green to prevent erosion and compaction from the pitter-patter and heavy footfalls of the animals. Any plant material with the ability to reseed and naturalize within the exhibit holds a distinct advantage in these tough conditions.
The best strategy is to plant early and often, hoping to engage the animal inhabitants with many types of plant options, including enrichment in the form of browse (cut material and leafy branches, sometimes with fruit or flowers). We seek to keep animals occupied by climbing on deadwood, swinging on ropes, and munching on browse that has been tossed into a hammock by a keeper, rather than destroying the landscape plants. All of these strategies work wonders to keep animals away from the live plants inside an exhibit.
From big statement pieces to the small flourishes, plant material has a positive effect on our animals’ homes, and it’s a part of being a zoo horticulturist that brings a great deal of satifaction. On your next visit to the Zoo or Safari Park, watch for the ways we use logs, branches, and plantings to help the animals thrive. Who knows, you might even get some ideas for your own pets at home!