Signs that an elephant is about to go into labor: loss of appetite, difficulty sleeping, and a pattern of "lying down, standing up, and lying down," says Colleen Baird of the Maryland Zoo, which is expecting its first elephant birth in its 132-year history any day.

Baird, the zoo's assistant elephant manager, says "general agitation" is all she has to go on until Felix's water breaks. And to prepare for that, Baird and her colleagues are keeping a round-the-clock watch, memorizing "elephant birth protocols," and stockpiling towels and wood chips.

"When an elephant's water breaks, it's not like a small water balloon popping," said Baird, 35, who has been sleeping in the zoo's elephant barn on a four-night rotation since Feb. 6. "We need the chips for absorption so we won't be slipping around."

And while talk of delivering an elephant -- and the bodily fluids that entails -- may turn some adults' stomachs, many children who visited the zoo during its opening weekend were fascinated. About 10,000 people, many of them children, visited the zoo on its opening weekend to see Felix, the city's newest media darling, and learn about the imminent birth of her calf.

Many visitors yesterday were surprised that they couldn't spot the pregnant elephant. The mammals, the largest on land, pass a lot of gas, and it's impossible to distinguish a baby from bloating, said Baird.

"How is the baby delivered?" Gretchen Dolan asked zoo education director Kathryn Foat as her 7-year-old son, J.T., and his friend Ben Luke, 7, listened.

"It's a stand-upper," Foat said.

Luke then asked how much the newborn would weigh.

"About 200 or so pounds, and it's as tall as a big St. Bernard," Foat explained, putting her hand up to Luke's chin to give the boy an idea of how large the baby elephant would be.

"I couldn't even pick it up," Luke said.

Most likely, only a handful of people -- veterinarians, zoo staff and maybe a few volunteers -- will get to witness the calf's birth, much less touch the youngster. The baby elephant won't go on display at the zoo until it's a few months old.

In the wild, elephants typically give birth at night while standing among other female elephants, experts say. The zoo's older female elephants, Dolly and Anna, most likely will be watching, Baird said. And if all goes well, all three females will care for the calf, which will be born with few survival instincts and require a lot of training.

"It takes a long time for them to grow up and learn where food is and how to use their trunk," Foat said.

Pregnancy lasts 22 months. Labor can last from 20 minutes to a day. In the end, the 200-pound baby just plops to the ground, Baird said. This is Felix's second pregnancy, which means that the delivery should go smoothly.

"It does make it easier because all of the necessary muscles have done the contracting and moving before," Baird said.

Felix, who is 24 years old, arrived at the zoo along with a male, Tuffy, from Riddle's Elephant and Wildlife Sanctuary in Greenbrier, Ark., in December. Felix was already pregnant, and no, Tuffy is not the father. They're just friends.

Since then, zoo staff have watched videos of "good and bad" elephant births, and the exhibit's manager has been present for a birth at Riddle's, Baird said. Once the baby arrives, zookeepers will monitor mother's and baby's weights, bowel movements, nursing routines, and activity levels.

"This is a great thing for the zoo because it will attract a ton of visitors," said Jayne Gerson, a former Philadelphia Zoo conservation officer who visited the exhibit yesterday with her daughter.

It also could generate much-needed money for repairs and maintenance. Foat said one zoo visitor yesterday asked whether Felix "was registered anywhere."

melissa.harris@baltsun.com