Sunday, December 08, 2024

Five wild animals that wont do it in cages


  • by Admin
  • 2024-09-02

Animals sometimes have to be locked up in order to save them. Captive breeding programmes are controversial insurance policies against extinction, but without them we would have lost several species, including Columbia Basin pygmy rabbits, Californian condors and the red wolf. But not all animals are willing.
Take corals. They may just look like colourful rocks, but coral sex is one of the most mystical sights the ocean has to offer – and one of the most difficult to reproduce in captivity. Now their secret may have been cracked. You can find out more here: “Playing Cupid to get reluctant corals in the mood for love“
From secretive cats to worn-out rhinos, here are five more of the hardest animals to breed in captivity.


1. Cheetahs
he first captive cheetah cub was born in 1956 at Philadelphia Zoo, very few breeding programmes have managed to mimic its success.
The main problem? Females are too secretive. “They have what we call a silent estrus,” says Adrienne Crosier, head of the Smithsonian Conservation Biology Institute’s cheetah breeding programme, meaning they don’t signal when they are ready to mate. To overcome this, Crosier and her colleagues use males as “on heat” detectors. After sniffing where a female has urinated, a male will bark if she is ready to mate.
This doesn’t solve the fundamental problem of inbreeding, a hangover from the Pleistocene, some 10,000 years ago. At this time most of the large megafauna – giant sloths, saber-toothed cats, dire wolves – succumbed to extinction. Cheetahs survived, but only just.
Extinction loomed again in the 20th century because of hunting and habitat destruction – 100,000 cats became 10,000, divvied into isolated populations. They inbred. Today, the survivors have low sperm counts, increased susceptibility to disease and wonky skeletons. Cubs frequently die before reaching adulthood.
To minimise inbreeding in captivity, males and females can have their genome sequenced and be artificially paired. That helps, but it’s not a complete solution. As with giant pandas (see below), cheetahs that are deemed genetic matches don’t necessarily want to mate.

2. Northern White Rhino
The northern white rhino was in the wrong place at the wrong time. As poaching increased in central Africa in the 1980s, political turmoil mired conservation efforts. By 2008, the subspecies was thought to be extinct in the wild. We now know there are three individuals left.
The male and two females are under armed guard day and night in their 600-hectare enclosure in Kenya, but they can’t breed. Aged 41, the male, called Sudan, “wouldn’t be able to mount”, says Richard Vignes, CEO of Ol Pejeta Conservancy, where the animals are kept. “He’s just too old and decrepit and his back legs are not in good enough working order.”
A couple of options are being discussed. The first involves IVF – but this has never worked in any rhino. And a female rhino’s cervix is corkscrew-shaped, meaning traditional ways of extracting eggs simply won’t work.
The second option is to use sperm from northern white rhinos to fertilise the eggs of the southern white rhino – a closely related species. The offspring would be hybrids but many of the northern white rhino genes would be saved.
Given the dire situation, the second option is more likely and promising, Vignes says. “To me, it’s not really about saving the species anymore. It’s much more about saving those genetic traits that allow rhinos to live in central Africa.”

3. Yangtze giant softshell turtle
The New Year brought tragic news for the Yangtze giant softshell turtle. On 19 January, Cu Rua was found floating in his lake in Hanoi, Vietnam. More than 100 years old, he was one of just four individuals left of this revered, spiritually significant species.
Two of the remaining turtles – a male and a female – are in captivity at Suzhou Zoo in China. The couple was introduced in 2008 and the initial signs were promising. “The male mounted the female 12 times,” says Gerald Kuchling, breeding programme leader for the Turtle Survival Alliance in Fort Worth, Texas.
Even so, they have had trouble conceiving. For one, they are both old – each over a century. And the male has half a penis. The tip was likely bitten off during an altercation with a rival male, who was killed. “The tip of a softshell turtle penis actually opens up like a flower. It’s quite an amazing structure,” says Kuchling. “But his looks nothing like this.”
In May 2015, Kuchling and his colleagues collected sperm by stimulating his penis with electricity and inseminated the female. The eggs were infertile. The team will try again in October.

4. Whooping cranes
By 1941, there were fewer than 20 whooping cranes left in the world. Two of these – Pete and Josephine – were kept at the Aubudon Zoo in New Orleans. In 1949, after a move to a more spacious outdoor enclosure, Josephine laid two eggs. Celebrations were short lived: they trampled the eggs, then Pete died.
With these failures and a precariously low gene pool, a new approach was needed. So starting in the 1970s, birds were artificially matched by computer program to maximise genetic diversity. Breeders would then artificially inseminate females with a chosen male’s sperm, collected by vigorously stroking the bird’s thighs and belly. “We’re trying to keep as much of the genome as we can,” says Marianne Wellington of the International Crane Foundation in Wisconsin.
Any offspring that hatched were then hand-raised by humans, each in complete silence, wearing a white cloak with an arm that looks like a crane’s head (shown above). The costumes are necessary to keep the birds “wild” and stop them becoming too acquainted with humans.
The efforts have paid off. Today, over 400 whooping cranes migrate from the marshes of Texas to Canada each spring to breed. A separate population has been coaxed into resuming another migration route by costumed researchers flying microlites.

5. Giant Pandas
Giant pandas are the mascots of low libido. Females are only in estrus for 24 to 72 hours a year. Even during this short window, males and females don’t always get it on.
With a wild population of around a thousand individuals in the 1970s, conservationists stepped in. They brought a number into captive breeding centres and tried to get them in the mood, giving them toys, water features, fruitcicles and playing recordings of giant pandas mating (see photo). They also collected sperm and artificially inseminated females.


The latter is largely responsible for a recent (and relative) panda baby boom. There are now more than 300 giant pandas living in zoos and breeding centres in Europe, North America, South-East Asia, Japan, China and Australia. The programmes were so successful that captive pandas were released back into the wild in 2007. There are now more than 1800 giant pandas in central China.


Despite the good news, giant pandas still won’t play ball. As with cheetahs and whooping cranes, conservationists have tried to pair individuals according to their genes. “The computer will say mate animal A to animal B,” says David Wildt, head of the Smithsonian National Zoological Park’s Center for Species Survival. “But those two animals could be like people in that they have sexual partner preferences.”


Now, with more giant pandas at their disposal, conservationists have begun trying another tack: let them decide between multiple mates. “If one animal isn’t a good mate then they can choose another,” says Wildt. With this option, not only did the pandas breed more often, but their offspring were healthier than those born as a result of artificial insemination.

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