Rare Sumatran tiger cub born San Francisco Zoo

A Sumatran tiger has given birth to a rare cub at the San Francisco Zoo, the second in only 30 years.

Zookeepers were thrilled with the arrival of the cute cub over the weekend as it provides a a rare boost to the critically endangered subspecies.

Veterinarians said the cub appeared healthy and active. They won't know its sex for at least two weeks, so they are simply calling the tiny, still-blind feline Junior, Cub or Baby, Corinne MacDonald, curator of carnivores and primates at the zoo, told the San Francisco Chronicle.

According to MacDonald, who is watching the cub on webcam video, the newborn was very active — an encouraging sign.

"It wiggles a lot and squirms a lot. The active part is what we really look for right now."

"Mom is really attentive; she's grooming, she's paying attention to the infant," MacDonald told the newspaper.

"The infant makes sounds, it coos. It'll scream and screech and cry when it gets real hungry. We can really see (Leanne) choosing to get up only when the infant is really sound asleep, so she's a great mother."

It was the first tiger born at the San Francisco Zoo since 2008, when tiger mom Leanne, aged 9, delivered a litter of three males, Reuters reported.

Before 2008, the zoo had not had a tiger birth in 30 years.

"These births are definitely rare," said Dr. Tara Harris, a tiger specialist with the North American accrediting group Association of Zoos and Aquariums.

It is welcoming news for zoo staff who were devastated on Christmas Day in 2007, when a tiger escaped from its enclosure and mauled one man to death and left two others seriously injured. 

The tiger was shot and killed by police after it charged officers.