A rare Sumatran tiger cub was born at the San Francisco Zoo over the weekend. Reuters reported that the rare cub is healthy. There are an estimated less than 400 Sumatran tigers in the wild, making this a critical event for the species.

Zookeepers were keeping watch of the mom and baby duo, who live in the Lion House via a webcam. The mother, Leanne, is 9-years-old.

"All signs seem to be positive so far," said Corinne MacDonald, San Francisco Zoo curator of carnivores and primates to Reuters."Mom and cub are bonding."

The cub who has yet to be named is the first tiger born at the San Francisco Zoo since 2008, when Leanne had three cubs. Those cubs were transferred to different zoos in the U.S. The tiger's father is a tiger named Larry who is six years old. Larry lives at the Audobon Zoo in New Orleans but was temporarily transferred over for breeding.

MacDonald said to The San Francisco Chronicle that for now they are calling the baby tiger Junior Cub or Baby.

The sex of the tiger is unknown until the cubs first exam two weeks after its birth. "These births are definitely rare," said Dr. Tara Harris who is a tiger specialist to Reuters. She added that there are 75 Sumatran tigers in captivity and they give birth to two to four litters per year.

Leanne did not get sedated during the pregnancy process and had prenanat sonograms while she was awake. "It's so much better for these animals not to have to be sedated. Many animals have adverse reactions to the anesthesia, which can be worse than the actual procedure," MacDonald said to Reuters.

Junior Cub will stay with the zoo for at least a year when they will decide to transfer or keep him at the zoo. "We really prefer to allow mom and cub to have a really solid two-week bonding time" before we get involved, MacDonald said to The San Francisco Chronicle. "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 added. "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."

The Sumatran Tiger is an endangered species  making these births an important achievement.

"We are thrilled with this birth," said Tanya Peterson, head of the zoo to The San Francisco Chronicle. "Sumatran tigers are a critically endangered species ... which makes every birth so impactful for these beautiful animals."