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Journalism of Courage
The Padmaja Naidu Himalayan Zoological Park (PNHZP) in Darjeeling has made headlines for successfully breeding 77 snow leopards since the 1980s, placing it next only to New York’s Bronx Zoo, which has produced 80 snow leopard cubs since it started breeding experiments with the species in the 1960s. Breeding wild cats in captivity, however, is notoriously difficult — their edgy temperament, unique physiology and genetic baggage make them erratic breeders. We explain.
Dubbed the ghost of the mountain, the snow leopard’s first record in captivity dates back to 1891 when the London zoo acquired one from Bhutan. But it was not until the 1950s that captive born cubs became breeders themselves. After that breakthrough in the Copenhagen zoo, snow leopards have bred relatively well in captivity. By 1991, 98% of all snow leopards in zoos were captive bred. Big cats are known to proliferate under unusual circumstances. The US alone has over 10,000 mostly inbred captive tigers — that’s twice the species’ count in the wild. South Africa banned captive lion breeding in 2021 but does not know how to deal with more than 6,000 captive lions living on private ranches. 
Avoiding such tragic outcomes is not the only challenge in big cat breeding. First, zoos need to eliminate triggers for stress. Clouded leopards, for example, did better when they were off display, not housed next to bigger cats like tigers, and provided with cage furniture that allowed activities such as climbing and hiding. Then there is the curse of genetic bottleneck. Most big cat species have suffered major population collapses in the past. When a population rebuilds itself from a handful individuals, it loses genetic variation, affecting the reproductive ability of individuals.
What further compromises the chances of conception in cats is their induced ovulation. They ovulate only while they are mating, and it takes multiple rounds for the physical sensation to activate a neural signal that triggers the hormonal response necessary for ovulation. Even artificial insemination (AI) cannot bypass these obstacles because the process requires anaesthetising animals before introducing sperm through the cervix into the uterus. In cats, sperm is propelled through the oviducts to meet eggs by muscle contractions. Anaesthetised females cannot make those contractions. A possible solution is to surgically put sperm onto the eggs inside into the oviducts. Laparoscopic AI has worked for tigers and jaguars. But the results have not been encouraging for cheetahs, a species unique among cats on multiple counts.In the social structure of other cats such as tigers or leopards, a large male territory encompasses multiple female territories to ensure female fidelity. It is the opposite among cheetahs: females roam multiple male territories to pair with multiple males and guard against further genetic constriction of the species. In captivity, the female cheetah is ‘turned off’ by loss of mating choice. There is no authenticated record of cheetahs breeding in captivity until 1956, when a cub was born in Philadelphia zoo. Even today, only one in five captive cheetahs, male or female, breed. Female cheetahs come to oestrus throughout the year but show few outward signs unless they are interested in mating. Misreading oestrus and giving male cheetahs access to a female not in heat can lead to serious injuries. 
George Schaller, the world’s preeminent field biologist, described a snow leopard spotting in the Himalayas: “Wisps of clouds swirled around, transforming her into a ghost creature, part myth and part reality… Balanced precariously on a ledge and bitterly cold, I too stayed, unwilling to disrupt the moment… Then the snow fell more thickly, and dreamlike, the cat slipped away as if she had never been.” (Stones of Silence, 1980) No zoo can recreate that magic. But the success of Darjeeling zoo is a significant contribution to the global captive stock which is considered an insurance for the snow leopard’s dwindling numbers — anything between 4000 to 7000 — in the wild. Today, 160 zoos across the world house over 600 snow leopards.
