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Gibbon Conservation Center Working to Save South Asia’s Hoolock Gibbons & Other “Small Apes”

During my stint in India last year, I did not journey across the Silliguri corridor to northeast India’s seven sister states. I knew of few westerners or East Indians who had done so. Nonetheless, I was eager to visit Assam—the centralized state in the northeast region of the country. Unlike most foreigners visiting the Bengal...

Adult female and young gibbon at the Gibbon
Conservation Center (Photo by Farrah Smith,
Sea Shepherd Conservation Society)

During my stint in India last year, I did not journey across the Silliguri corridor to northeast India’s seven sister states. I knew of few westerners or East Indians who had done so. Nonetheless, I was eager to visit Assam—the centralized state in the northeast region of the country.

Unlike most foreigners visiting the Bengal region, I was not in search of an Indian rhino, Indian elephant or even a Bengal tiger in the wilds of South Asia.

My purpose for crossing the corridor was to see two of India’s rare primates—the eastern and western hoolock gibbons.  Both species still occur in India and both are quite imperiled.

One literary source indicated that as few as hundred eastern hoolock gibbons are suspected to still occur in the Indian state of Arunachal Pradesh, and suggested that almost the entire Indian population of western hoolock gibbons lives inside Assam’s famed Hoolongapar Gibbon Sanctuary (HGS).  But the eminent naturalist Dr. Anwaruddin Choudhury said, “Those 160 are not eastern hoolocks and that western hoolocks are found in sanctuaries in Barail, Dihing-Patkai, Marat Longri and East Karbi Anglong.”  Fewer western hoolock gibbons live in adjoining states in the northeast region of the country.

According to Dr. Choudhury, “The western hoolock is still widespread in Assam, Arunachal Pradesh, Manipur, Meghalaya, Mizoram, Nagaland, Tripura and adjacent areas of Bangladesh and Myanmar.” “However,” he said,  “In many smaller pockets it has vanished or is nearing extirpation.”

Alma Rodriguez of the Gibbon Conservation Center
(Photo by Farrah Smith)

Records indicate that Assam may have supported as many as 80,000 western hoolock gibbons in the 1970’s and estimates suggest that as few as 5,000-6,000 individuals survive in the tropical and sub-tropical evergreen forests of the protected area.

The region’s flora includes some broad-leafed species and coniferous species, but deciduous and scrub forest is uncommon in the sanctuary.  Mangrove forests are entirely absent.

The Hoolongapar Gibbon Sanctuary is home to several other primate species, including Bengal slow lorises, four species of macaques (i.e., stump-tailed, northern pig-tailed, rhesus and eastern Assamese) and capped langurs.

But it was the hoolock gibbon that the late Minnesota Zoo tiger biologist Dr. Ron Tilson began studying early in his career that launched his interest in the megafauna of this region and subsequent conservation efforts for the Bengal tiger.  Ron passed away last year, and it was in writing this tribute to him that I learned of his early work with hoolock gibbons.

Ron studied the foraging and nutritional ecology of hoolocks and found that similar to other gibbon species, which are also arboreal and diurnal, the hoolock is a frugivorous species.  It is in part through Ron’s field investigations that we learned just how much gibbons like figs among available foods.

Hoolock gibbons comprise two of the 16 species of acrobatic, brachiating, bipedal primates that we traditionally call “lesser apes.”  Hoolock gibbons are the only apes, large or small, found in India, and indeed they are endangered. In fact, the western hoolock gibbon was ranked as one of the 25 most endangered primates in the world as recent as 2009. The eastern hoolock gibbon is listed as Vulnerable on the IUCN Red List. The western hoolock is listed as Endangered.

Members of this primate family (Hylobatidae) are what you and I would most probably call gibbons, but as mentioned, scientists might commonly call them lesser apes. Noted conservationist Dr. Jane Goodall would prefer that primatologists and primate enthusiasts refrain from labeling them with what was once such commonly used nomenclature. She’d much prefer these “lesser apes,” if anything, be referred to as “smaller apes” to better dignify them as she states in the Gibbon Conservation Center video on the home page of the organization’s website.

Sadly, in the realm of conservation branding, the gibbon may suffer. After all, it is closely related to humans and other hominids and yet few people could probably name how many species exist, much less provide the name of any individual species. The gibbons, almost all of which were once classified in the genus Hylobates, may not be as well known as the great apes, but they are no less charismatic.

As a taxonomic group, gibbons include, by far, the most endangered of primate species and mammals, for that matter, on Earth. In fact, some species from Southeast Asia number fewer that 20 in the wild.

Great and “smaller” apes are comprised of two families, respective of size. These include the well-known hominids—humans and the six species of great apes (i.e., two orangutan species, two gorilla species and the chimpanzee and bonobo) and the gibbons or hylobatids.

Gibbons are the only anthropoid mammals found in continental Asia. Beside humans, the western and eastern hoolock gibbons are the only extant apes occurring as far north and west in the Eastern Hemisphere as northeast, India. Other species of gibbons are found farther east in continental Asia.

The late Alan Mootnick, founder of the Gibbon Conservation Center (GCC) in Santa Clarita, California, which is outside of Los Angeles, was instrumental in taxonomic reclassification of the hoolock gibbon. The two species were once considered to be one species, comprised of two subspecies.

At one time both the hoolock gibbons species were placed in the genus Bunopithecus (now extinct)Mootnick reclassified the two subspecies as two distinct species and placed them in the genus Hoolock.  However, Dr. Choudurhury contends in a recent paper that the Hoolock spp. should only be recognized at the subspecific level. Just last year, he described a new subspecies—Hoolock hoolock mishmiensis.

Hoolocks are the largest gibbon species in the world next to the Siamang. According to the GCC staff, the name “hoolock” is derived from the onomatopoetics of their song. Different gibbon species have different songs.

The western hoolock is the nominate subspecies (Hoolock hoolock). Besides its distribution in India, it ranges throughout parts of Myanmar and Bangladesh. The eastern hoolock is reported to occur in Myanamar and in China’s Yunnan Province. The Chindwin River in Burma is considered a natural boundary to gene flow between the two species. The Chindwin flows into the famous Irrawady River, which is known for the Irrawady River dolphins. A natural hybrid zone occurs at the headwaters of the River.

The Gibbon Conservation Center currently houses a family of eastern hoolock gibbons among its resident apes. The Center is dedicated to providing sanctuary for gibbons in need of life long care and propagation of rare gibbon species. The facility currently houses approximately 40 gibbons, representing four genera and five species.

The center works with captive wildlife facilities around the world to help secure a healthy and sustainable captive gene pool. This includes participation in the American Zoo & Aquarium Association’s Species Survival Programs for the taxon.

North American zoos have decided to focus conservation breeding efforts on Javan, white-handed, white-cheeked and siamang. Species like the gray or Mueller’s gibbons, which Nat Geo’s own Joel Sartore recently featured in a piece on endangered zoo animals, are being phased out of breeding programs in favor of more endangered gibbon species. As for the western hoolock gibbon, Dr. Choudhury said “There is no need for any captive breeding as of now and need of the hour is to adequately protect the larger habitats, many of which are protected areas.”

My colleague Ronda Schwetz, a captive primate husbandry expert and Director of the Henry Vilas Zoo in Madison, Wisconsin said she hopes her work and that of her colleagues with umbrella species in Southeast Asia, like orangutans and sun bears, “positively impacts gibbons,” which she considers undervalued and immensely charismatic.

To see hoolock gibbons in the wilds of India, one must visit the northeastern states. Assam and the other six sister states of the region are accessed in country via the Siliguri corridor. Abutting Nepal to the north and Bangladesh to the south, this strip of land, at it’s narrowest, is only 14 miles wide.

Surrounded by the six other sister states, Assam defines the Brahmaputra and Barak river valleys, an expanse of land comprised of over 30,000 square miles.

Known for conservation efforts, which ultimately saved the Indian rhinoceros from extinction and as a remnant and last wild place that can call the Indian elephant home, the state of Assam has emerged as an ecotourism destination.

Dr. Jordan Schaul and Farrah Smith

I toured the Gibbon Conservation Center a few weeks ago with a small party that included actress and recognized primate conservation activist Charlotte Ross. Charlotte has been instrumental in lobbying for welfare initiatives on behalf of the great apes and said that she was “most impressed with the care provided for the gibbons at the GCC.”

Charlotte got an opportunity to observe Alma Rodriguez demonstrate the hand-rearing and reintroduction techniques followed by the GCC. An infant eastern hoolock gibbon was separated from his mother due to complications. Alma brought the infant to his mother, monitoring their interactions closely, allowing them to maintain their bond.

Alma, a staff member at the GCC, was feeding the infant outside of an enclosure with both gibbon parents looking on.

“Initially, we brought the infant inside because his mother wasn’t producing milk. Phu Gyi is a female eastern hoolock, and we’ve yet to officially name the little one,” Alma said. “Our goal is to maintain a strong bond between Phu Gyi and her son until we can reintroduce them to each other. He’s less than two months old, but often sings along with the rest of his family during his daily visits.”

The GCC’s Executive Director Gabi Skollar said, “In this case human intervention is necessary, and an infant has to be removed from its mother.  The staff follow careful protocol to hand-rear the infant and reintroduce it to their natal family as early as possible so that it can learn and develop normal social behavior.”

Farrah Smith, a wildlife activist and executive with the Sea Shepherd Conservation Society, also on the tour, said, “The mother gibbon, may have acted aggressive according to Alma, but was showing nothing but love, trust and gratitude towards her when she observed them.”  She later said, “At one point the mother was even grooming Alma’s hair while she held her baby.”

Impressed by the husbandry standards of the facility, Farrah said, “The exemplary care provided by the staff, speaks to the organization’s commitment to both the welfare of their individual captive residents and conservation of wild populations, as some of the gibbons at the GCC could be candidates to be reintroduced to the wild.

Alma with gibbons (Courtesy GCC)

Charlotte Ross is quite familiar with the plight of Africa’s apes and the orangutan, but as a well-known lobbyist on behalf of primates said, “The plight of these smaller apes is just as catastrophic as it is for great apes.” She said, “We need to draw attention to gibbons before more species’ populations reach numbers of twenty or so, or reach the point that conservation efforts for them are deemed futile.”

Sadly, wild populations of hoolock gibbons require human action and intervention for their continued survival.

Drs. Awadhesh Kumar and Jikom Panor from the Hoolock Gibbon Conservation Breeding Centre in Itanagar, Arunachal Pradesh, India presented a paper at The 1st International Gibbon Husbandry Conference in June of 2012. The authors asserted that eastern hoolock gibbons are subjected to several anthropogenic threats, including expanding tea plantations, other agriculture activities and deforestation.

A declining wild population of approximately 500 individuals prompted the development of a conservation breeding centre, which was established in 2007 as part of ‘National Hoolock Gibbon Conservation and Breeding and Rehabilitation Programme’ at Biological Park, Itanagar, Arunachal Pradesh.

I also learned from my colleague Dr. Shirley McGreal via an email correspondence about recent efforts to restock western hoolock gibbons through the help of the Sonja Wildlife Rescue Center’s HURO Program based out of the Forest Complex, Dakopgre, 794001 Tura, Meghalaya, India. The future for the hoolock gibbons is uncertain, but efforts are clearly underway to save them.

Note from Jay Petersen, Curator of Carnivores and Primates at Chicago’s Brookfield Zoo. Jay coordinates all gibbon conservation breeding programs for the North American-based Association of Zoos and Aquariums. (updated March 7th 2014)

“Chicago Zoological Society’s Brookfield Zoo manages and exhibits white-cheeked gibbons.  We currently care for a family group which includes a mated pair – 28 year old male, Bennie, and 25 year old female Indah, a 4 year old subadult male Thani, a 2 year old juvenile male Coung and a birth expected in may 2014.   Since beginning my work in zoos in 1979 I have heard the AM duets of white-cheeked gibbons, 1st at the Minnesota Zoo and now at Brookfield Zoo.  Their long calls are clear and penetrating.  They carry throughout the exhibit buildings where they are housed and have become a familiar aural background.

Zoos strive to be educational and inspirational and to create an appreciation for wildlife and the natural world, which fosters support for conservation initiatives. As products of the natural world, ourselves, we are enchanted with wildlife and dependent upon nature, beyond our understanding.   Despite our fascination with wildlife and nature it seems to remain our human endeavor to create an unprecedented disruption and loss of natural habitats and ecosystems.

Gibbons/siamang (Hylobatids) being arboreal specialists are particularly sensitive to the loss of mature tropical forest.  Although they are quite adaptable primates, they are unable to self-sustain following the loss of food resources  or in the face of persistent hunting.

Of the 16 species of hylobatid listed on the IUCN Redlist 3 are listed as Critically Endangered, 12  as endangered and one as vulnerable (  The Association of Zoos and Aquariums (AZA) provides organization and oversight  for the management of Species Survival Programs (SSP), cooperative population  management and conservation programs, which maintain healthy and self-sustaining  populations that are genetically diverse and demographically stable.

White-cheeked gibbons, lar gibbons and siamang are managed through Species Survival Programs.  Smaller populations of other hylobatid species are managed in AZA and non-AZA zoos and sanctuaries throughout North America.  These species include red-cheeked gibbons, agile gibbons, Mueller’s gibbons, Javan gibbons, pileated gibbons and eastern hoolock gibbons.

The Gibbon Species Survival Programs provide transfer and breeding recommendations to the cooperating institutions and advises gibbon managers and caregivers regarding all aspects of gibbon/siamang management and care in living collections.

We are beginning to coordinate our SSP programs with similar programs in Australia and Europe through the exchange of gibbons/siamangs and management information to the benefit of all regions.  In addition to cooperating institutions the SSP is comprised of a small volunteer management group with good gibbon care experience, a small group of advisors including veterinary and  nutritional advisors and the very important studbook keepers for each species who keep an historical record of zoo gibbons and their pedigrees.

Many of the zoos managing gibbons/siamangs also provide support for conservation  and field projects in gibbon range countries.  The AZA Ape Taxon Advisory Group  (TAG), which provides organization and oversight for all the ape SSPs in AZA, provides significant grant money for ape conservation through the AZA Ape TAG Conservation Initiative.

Our ultimate goals remain focused on the protection and conservation of natural habitats and ecosystems, including the hylobatids supported by them.  Benny, Indah, Thani and Ceung are ambassadors for their respective critically endangered species.  As individuals and a species they are cared for day after day.  Hearing about natural habitats that have fallen silent, where gibbon long calls are no longer heard, suggests a future where these ambassadors may play a role in returning one small portion of an ecosystem back to the wild.”

Dr. Jordan Schaul’s profile


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Meet the Author

Author Photo Jordan Carlton Schaul
With training in wildlife ecology, conservation medicine and comparative psychology, Dr. Schaul's contributions to Nat Geo Voices have covered a range of environmental and social topics. He draws particular attention to the plight of imperiled species highlighting issues at the juncture or nexus of sorta situ wildlife conservation and applied animal welfare. Sorta situ conservation practices are comprised of scientific management and stewardship of animal populations ex situ (in captivity / 'in human care') and in situ (free-ranging / 'in nature'). He also has a background in behavior management and training of companion animals and captive wildlife, as well as conservation marketing and digital publicity. Jordan has shared interviews with colleagues and public figures, as well as editorial news content. In addition, he has posted narratives describing his own work, which include the following examples: • Restoration of wood bison to the Interior of Alaska while (While Animal Curator at Alaska Wildlife Conservation Center and courtesy professor at the University of Alaska) • Rehabilitation of orphaned sloth bears exploited for tourists in South Asia (While executive consultant 'in-residence' at the Agra Bear Rescue Center managed by Wildlife SOS) • Censusing small wild cat (e.g. ocelot and margay) populations in the montane cloud forests of Costa Rica for popular publications with 'The Cat Whisperer' Mieshelle Nagelschneider • Evaluating the impact of ecotourism on marine mammal population stability and welfare off the coast of Mexico's Sea of Cortez (With Boston University's marine science program) Jordan was a director on boards of non-profit wildlife conservation organizations serving nations in Africa, North and South America and Southeast Asia. He is also a consultant to a human-wildlife conflict mitigation organization in the Pacific Northwest. Following animal curatorships in Alaska and California, he served as a charter board member of a zoo advocacy and outreach organization and later as its executive director. Jordan was a member of the Communication and Education Commission of the International Union for the Conservation of Nature (CEC-IUCN) and the Bear Specialist Group of the IUCN Species Survival Commission (BSG-SSC-IUCN). He has served on the advisory council of the National Wildlife Humane Society and in service to the Bear Taxon Advisory Group of the Association of Zoos and Aquariums (AZA Bear TAG). In addition he was an ex officio member of council of the International Association for Bear Research and Management. Contact Email: