Little did we know the mischievous looking Brown-throated three-toed sloth (Bradypus variegatus) would become such an integral part of our collection at The Dallas World Aquarium when our permit request was approved by MINAE, Ministerio del Ambiente y Energia (Ministry of Environment and Energy) Costa Rica. Prior to Leno’s transfer to the DWA on June 22, 2005, the orphaned infant had been cared for at the Sloth Sanctuary near Limon, Costa Rica for four years. Leno’s birthday, determined by the Sanctuary, is October 1, 2001.
In order to learn about the feeding preferences, medical issues and general behavior of these animals, several years prior to Leno’s arrival had been spent researching and observing Brown-throated three-toed sloths (Bradypus variegatus). Fifteen years ago (Winter 1998, DWA Newsletter) I wrote my first article about this species, which included:
The sloth has little muscle mass and mobility; instead it has adequate space for storing and processing large amounts of difficult-to-digest food (a full stomach may weigh approximately one-third of the total body weight). The large, multi-chambered stomach contains bacteria that allow for the fermentation and break down of cellulose into starches and sugars. Sloths digest their food for a very long time in order to extract the maximum amount of energy. Food may be digested for a month before moving into the small intestine. Defecation occurs on an average of once every eight days, helping the sloth conserve water which is not easy to obtain while hanging upside down in a tree. This weekly process is quite arduous for the sloth who goes to the ground, digs a small hole for his excrement, covers it, and climbs back to the top of the tree. This ritual may be to provide nutrients for the host tree and/or to hide the odor of the feces from predators.
Three-toed sloths are the most common of all sloths, but they are seldom exhibited. Their adaptations present a challenge for zoo environments. Keeping a fresh supply of leaves is the first hurdle. At one time it was thought that three-toed sloths eat only the leaves of the Cecropia tree but it is now known they eat leaves from a wide variety of trees. With such slow metabolism, signs of illness or malnutrition are sometimes too delayed for medical procedures to be effective.
The three-toed sloth at The Dallas World Aquarium will be in a new exhibit — Sloth Forest. These animals were transferred from a free roaming zoo in Barquisimeto, Venezuela where their primary diet consisted of leaves from the Monkey Don’t Climb tree (Chorisia speciosa) and the common rubber tree (Ficus elastica). Sloth Forest will contain both species of plants. Additional chorisia will be supplied from both the west and east coasts. Depending upon the season (chorisia is deciduous). This will be the first three-toed sloth on exhibit in the United States since the 1970’s. An equally impressive leaf-eater, the Australian Koala, lives and breeds in zoos throughout the world. We are hopeful that constant monitoring of behavior and nutrition will allow us to keep a seldom seen and unusual animal whose “slowness” has allowed it to survive in the wild — perhaps allowing other institutions to benefit from our experience.
In The Director’s Notes, Spring 2001-DWA Newsletter, my comment was brief and less exciting —
The Dallas World Aquarium recently lost one of its most significant and charismatic animals. Due to complications from pituitary failure, the ten year old female sloth died on March 17. While not endangered in the wild, “Lucky” became the longest living captive Three-toed sloth (Bradypus variegatus) in the world. Lucky arrived in Dallas on July 30, 1998 from Barquisimeto Zoo and immediately became a popular attraction in the Venezuelan ORINOCO – Secrets of the River exhibit. Lucky provided us with amazing insights on the care and maintenance of specific folivores…. We will all miss Lucky, however, The Dallas World Aquarium feels confident in keeping this species in Dallas for many years to come.
After determining their preferred or perhaps the most readily available food source in their native habitat was the leaves of the Cecropia tree, finding a constant food source was imperative. For the past eight years, since Leno’s arrival, these leaves have been flown on a weekly basis to the DWA from Hawaii. Leno’s diet has now expanded to include leaves from not only Cecropia (Cecropia peltata), but Ficus alii (Ficus binnendijkii), Monkey don’t climb (Ceiba speciosa), Shaving brush (Pseudobombax ellipticum) and Chocolate (Theobroma cacao) trees. As a backup food source, should a flight be delayed or cancelled, the Cecropia, Monkey don’t climb, and Chocolate trees are part of the DWA rainforest and can easily be gathered if needed. Leno’s weight upon arrival in 2005 was 3.96 kilograms, with his average weight now being 5.5 kgs.
Since 2011, the Zoologico de Brasilia has been studying the Brown-throated three-toed sloth (Bradypus variegatus) in captivity. Eight specimens have been part of the study (with six being alive at the present time) and although not an endangered species, they are hoping to determine the best way to keep the animals. They have offered much the same diet as the DWA — Cecropia sp, Theobroma cacao, and also Malvaviscus arboreus (of the hibiscus family). Endemic only to Brazil, the endangered Maned three-toed sloth (Bradypus torquatus) is threatened due to deforestation, habitat fragmentation and isolation of populations. Hopefully their work with the Bradypus variegatus will provide insight in how to save the Maned three-toed sloth. By sharing experiences, we are able to learn from each other. For example, our findings on sloth’s susceptivity to Toxoplasmosis can also help create sanitary protocols.
The Two-toed sloth (Choloepus hoffmanni) can also be seen at the DWA. But it is the always smiling Three-toed sloth that is a favorite of all ages. Judy Arroyo, founder of the Costa Rican sanctuary, with whom we have had a conservation/education partnership since 2003, remains in close contact with the DWA, visiting annually (accompanied by the resident Sanctuary veterinarian) to check on Leno’s welfare. As stated by Judy, “the DWA has generously provided computers, medical and dietary supplies to the Sloth Sanctuary. They had the architectural plans designed for our medical facility known as the ‘Slothpital’. If we really need something, they are always ready and willing to help. Staff from the Sloth Sanctuary and DWA are provided training at both facilities. This allows the staff of DWA to learn about the animals in their natural environment and for our staff to periodically check in on the sloths at the DWA.”
Judy continues by adding “Over the years, the DWA has played an integral part in the Sanctuary’s conservation and education programs, supporting our work with sloths. Both Bradypus varietagus and Choloepus hoffmannis from the Sanctuary are now at home in the beautiful Aquarium. Leno, a handsome Bradypus male holds court in his open-air grove of trees at the Aquarium, charming visitors.”
Judy has planned her annual visit to the DWA for late September. Although she will not be here on Leno’s 12th birthday, with his nonchalant personality, we are fairly certain that he will show no more than his usual enthusiasm while he enjoys his Cecropia pods as he hangs out in the branches on the third level of the rainforest.