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October 21, 2005
Monkeys under zoo stress
Cage jitters: A monkey in captivity. Picture by Prem Singh
New Delhi, Oct. 20: A lion-tailed macaque in a southern Indian zoo appeared to be locked in a death duel with its own arm. Several times a day, it would bite its own wrist, tear off skin and hurt its own wounds. In Kanpur zoo, a stump-tailed macaque succeeded in biting itself to death.
In over 20 months of observing the behaviour of monkeys in Indian zoos, wildlife biologist Avanti Mallapur has picked up hard evidence of bizarre behaviour displayed by several species of monkeys maintained in captivity. One female macaque created bald patches on her infant by incessantly plucking its hair.
Her study, the longest to observe non-human primate behaviour in Indian zoos, has revealed disturbingly high levels of abnormal behaviour in several species of captive monkeys.
Scientists believe the strange behaviour results from the stress of living in zoos that have failed to provide the natural and social environments in which the monkeys have evolved.
Wildlife scientists say the study has exposed gaps in zoo management practices in India. "It's not because of any specific zoo manager or a particular zoo enclosure," said Mallapur, at the National Institute of Advanced Studies (NIAS) in Bangalore. "It's a nationwide systemic problem."
Mallapur studied 52 lion-tailed macaques and 11 species of other macaques and langurs housed in 12 zoos, using pencil and paper to record what she saw or video cameras to grab shots of monkey enclosures every five minutes.
Half of all the monkeys that she studied displayed some form of abnormal behaviour.
The studies showed that the design of the monkey enclosure influenced behaviour, Mallapur said, reporting her findings in the latest issue of the journal Current Science.
Macaques housed in cages with a hard floor, for instance, exhibited higher levels of abnormal behaviour than monkeys in open-moated enclosures with soft ground.
Enriching the enclosures with different play objects also helped the monkeys.
"Macaques are social animals and it's important to maintain enclosures with the right numbers of animals and in the right sex ratios," said Anindya Sinha, primate behaviour specialist at the NIAS who was Mallapur's doctoral guide.
In most Indian zoos, monkeys are rarely housed in groups of more than five.
In most zoos, one or two individuals are confined to a caged enclosure. "Some monkey species have social organisations that require two or three males in large enclosures with five to 10 females," said Sinha.
"Keeping a single male with a single female won't necessarily lead to mating," said Sinha.
The stress emerging from long periods in relative confinement would show up as abnormal behaviour which, in turn, is likely to have negative effects on breeding.
The higher the level of abnormal behaviour, the lower the breeding success.
"The most frightening behaviour is the floating limb syndrome," said Sinha. One of the limbs of the animal rises gradually into the air and the monkey struggles to wrestle it back into its normal position, repeatedly biting it in the process.
Primate scientists say several zoos in the US and Europe have demonstrated captive breeding of lion-tailed macaques, an endangered species now found only in the rain forests of India's Western Ghats.
"There's a need for crosstalk between wildlife biologists and zoo keepers in India on how to make available space that mimics their natural environment," said Sinha.
It might not really require too much of extra funds or resources to achieve this, said Mallapur. "Even bamboo or other inexpensive materials could be used by zoo staff to enrich the environment within the enclosures.
"The lack of behaviour studies in Indian zoos has led to a situation where zoo staff remain oblivious of the condition of captive non-human primates in zoos," she said.