A diverse array of animals resides in the Small Mammal House, ranging from primates to armadillos. These animals occupy various niches in the wild and have evolved highly specialized behaviors to adapt to their native environments. Here at the Zoo, keepers design environmental enrichment activities to encourage these natural behaviors.
Stimulating species-typical behaviors through enrichment improves the well being of animals in captivity. It also improves reintroduction success by maintaining behaviors critical to survival in the wild and improves the success of captive breeding by encouraging normal social interactions among individuals. Finally, enrichment gives Zoo visitors a chance to witness animals in true form, behaving much as they would in their native habitats.
The Zoo’s keeper staff often use holidays as an opportunity to give variety to both visitors and the animals in their care.
Golden Lion Tamarins and Golden-headed Lion Tamarins
In their native Brazilian coastal forest habitats, lion tamarins forage for insects using their slender fingers to search bark, bromeliads, and other tiny nooks—a behavior called “micromanipulation.” Keepers elicit this behavior in the Zoo's lion tamarins by placing log feeders—logs with small holes drilled in them—in the animals' enclosures. The tamarins poke their long fingers into the holes to retrieve worms and crickets that keepers have planted inside.
Wild tamarins also scour the forest canopy for fruit, but in the jungle, the tastiest fruit is not always within easy reach. Several times a week, keepers at the Zoo string whole pieces of fruit six inches below branches, giving tamarins the opportunity to hang, reach, and creatively maneuver for the treats. Chasing after live crickets in their enclosures is another way the tamarins express natural behaviors to obtain their food.
Geoffroy's Tufted-eared Marmosets
Marmosets are gumivores—tree sap is a large component of their diets—and they have teeth specially designed to get at the sap. Their lower incisors jut out at an angle allowing them to access sap by puncturing holes in trees, an activity referred to as “gouging.” In the wild, marmosets will gouge holes into trees and then wander off until the viscous sap has begun to flow. By the time they return, insects that have become trapped in the sticky stuff make for an extra protein-packed snack.
To give marmosets in the Small Mammal House the chance to express this natural behavior, keepers reconstitute powdered tree gum (an ingredient used in pastries and available from many bakeries) and inject it into hollow logs with holes drilled into them. After the marmosets have licked up the sap, they puncture the log with their incisors to retrieve more.
Naked and Damaraland Mole-rats
In the wild, mole-rats tunnel underground and eat tubers that plunge below the soil. To simulate this behavior in captivity, keepers leave hunks of carrots, beets, and other root vegetables in the mole-rats' tunnels, sometimes blocking the tunnels completely. The mole-rats manipulate and gnaw their way around the veggies.
Black Howler Monkeys
In the rainforests of Latin America, howler monkeys bellow out territorial calls to locate neighboring troops. To elicit vocalization from the pair of howlers when they first arrived at the Zoo, keepers exposed them to a variety of music and sounds. Discerning listeners, the howler monkeys made no response to classical music, heavy metal, Enya, or soothing nature sounds. At first, only the sound of a leaf blower or lawnmower would incite their rumbling vocalization. Today, the pair of howlers needs no invitation to let loose a thundering roar.
Because howler monkeys frequently encounter other troops in the wild, they are accustomed to seeing other individuals. Keepers give the Zoo's howler monkeys non-breakable mirrors. The monkeys believe their reflections are other howler monkeys.
Red-ruffed Lemurs: Enrichment as Therapy
When keepers became concerned with the health of a female lemur that had lost her mate, they used enrichment to treat her depression and poor appetite. They groomed and massaged her, played lemur videos and sounds, and gave her a life-sized lemur plush animal, which she groomed and slept with. They also moved her into the Small Mammal House's mixed-species exhibit where she could be stimulated by the sights, sounds, and smells of other animals, as she would in the wild. She now has the company of a male red-ruffed lemur, and they groom each other frequently.
Mixed-species exhibits may encourage symbiotic or complementary relationships among animals that would share common habitats in the wild. Watch the mixed-species exhibit in the Small Mammal House long enough and you might catch a golden lion tamarin grooming an iguana or riding through branches on the stomach of a two-toed sloth!