Ocean Park eager for signs rare alligator is pregnant
There are signs that two of Ocean Park's four Chinese alligators, an endangered species, may mate this year in what could be a breakthrough for the park's ambitious breeding programme.
Signs of a successful mating should be evident by the end of August, chief veterinarian Dr Paolo Martelli said. The peak mating period is in June and July with eggs usually laid in September. Alligators hibernate during winter.
'I've seen them being very close but I haven't actually seen them mating,' Martelli said.
'At the moment, what we are doing is waiting for the female to show some signs of nesting.'
Building a nest indicates the female, which has been exerting her dominance over the other two females, is pregnant and ready to lay eggs. Twigs, leaves, soil and other materials have been placed in the alligators' new enclosure in preparation for possible nest building. The other two females were moved out of the enclosure late last year and are no longer on public display after the dominant female became aggressive.
Martelli said he decided not to subject her to an ultrasound scan to avoid stressing her, something that could ruin any chance of a successful mating this year. Instead, he is scanning the other two females to check the development of their ovaries in the hopes this can give an indication of the dominant female's reproductive development. All the females are about nine years old and Chinese alligators generally become sexually mature from the age of seven.
However, recent scans on one of the other females showed that her ovarian follicles, which contain the eggs, were not yet fully developed, meaning she was not sexually mature, Martelli said.
Chinese alligators enjoy long lives and females can lay up to 40 to 50 eggs at a time. Given the relatively young age of the dominant female, Martelli said he would be happy to get about 20 eggs. The sex of alligator offspring is determined by the temperature, with lower temperatures resulting in mostly females and higher temperatures of between 32 and 33 degrees Celsius giving mostly males. Martelli said he expected to incubate eggs from the dominant female at 31 degrees, which should yield roughly equal numbers of males and females.
Ocean Park acquired the four Chinese alligators, which are native to the Yangtze River, in 2003. The species is classified as critically endangered with 150 estimated left in the wild, although many more are bred in farms and zoos around the world. In recent years, the species has gradually been reintroduced into their natural habitat.
Unlike in the wild, where alligator eggs are often easy prey for predators, 90 per cent of the eggs can be expected to survive with incubation. With the possibility of having many more Chinese alligators through a single successful mating, the other two females might be traded for other animals Ocean Park needs. Gary Abel, general curator for zoological operations and education at Ocean Park, said there were talks with Singapore to trade the other two females for two or three capybaras, the biggest rodent in the world. The trade is expected to be completed before the end of this year. The capybaras will be part of a new South American exhibit at the marine park.
About 90 per cent of the species on display at Ocean Park are obtained via such trades and exchanges, including some jellyfish, stingrays and dolphins.
