Is she or isn't she?

Like speculation over celebrity baby bumps, everybody is excitedly wondering about Chrissie.

The Honolulu Zoo's 9-year-old Sumatran tiger might be pregnant. Probably is pregnant. But no one is willing to call it a sure thing yet.

All the signs are there, but it's not like you can give a lady tiger a pregnancy test stick and show her to the restroom.

Zoo officials know she "got together" with her mate Berani in the early part of June. They know she hasn't come into estrus again in the last two months. And they say she looks like she's gaining weight.

"But we won't do anything like try to weigh her," said Sidney Quintal, director of the city Department of Enterprise Services, which oversees the zoo. "We don't want to do anything that might involve getting a pregnant mother excited."

Other types of tests, even palpating her belly or doing an ultrasound, are no easy feats with a tiger.

As Quintal puts it, "She's a Category One animal." You don't want to mess around with those.

But lately, she's been acting different. She's been sweeter, more affectionate with her zookeeper, who sees her every day and has been noticing the little changes.

Tommy Higashino, acting zoo director, says the whole zoo is on pins and needles waiting to know for sure. Being a conservative man, he's not willing to call it a go until two weeks before the birth, when various physical changes will make the pregnancy undeniable. The gestation period for a tiger is short, around 100 days, so Chrissie could deliver a litter of tiger cubs around the first week of September.

"The last time tiger cubs were born at the Honolulu Zoo was in 1981," Higashino said. Chrissie and Berani have had cubs together before, at the Fort Wayne Children's Zoo in Indiana. The two came to the Honolulu Zoo on indefinite loan in November 2005 and their new tiger habitat, built with cub-making in mind, opened this spring.

The city is working on a plan to set up cameras to stream live video of the birth so that zoo staff and the public can watch remotely.

"We have to follow the protocol established by the Sumatran Tiger Group," Higashino says, "That means give her space and privacy."

The cubs would be sequestered for their first four to six weeks before being introduced to the public. They would stay with their mother at the zoo for the first two years of their lives, as part of the international Species Survival Program protocol.

Quintal isn't ready to say that the pregnancy is confirmed, but he notes, measuring his words, "With reservation, we're very hopeful."

But then, the excitement of possible tiger babies breaks through: "We feel like we're going to be uncles and aunties!"