Pittsburgh Zoo visitors could see some hot and very heavy action in coming days as black rhinoceroses Azzizi and Jomo meet and mate for the first time.

The courtship and coupling of the two-ton animals, if it occurs, has the potential to be violent, loud, lengthy and Earth-moving in a most literal sense, said Dr. Barbara Baker, Pittsburgh Zoo & PPG Aquarium president and chief executive officer.

"The courtship is usually very entertaining. It can be aggressive, loud and vocal with head-butting and hitting and nipping," Dr. Baker said at a news conference yesterday outside the one-acre rhino yard where the mating will take place. "He chases her. She chases him. They make a lot of noise.

"We just want to alert zoo visitors and make sure they know it's OK."

Azzizi, a 10-year-old female born at the Cleveland Zoo, and 14-year-old Jomo, who was born at the San Diego Zoo and came to Pittsburgh when he was a year old, are housed in adjacent stalls in the zoo's rhino barn but have never been together outside in the public yard. Rhinos in the wild are solitary animals except during mating season.

Dr. Baker said that when Azzizi, begins her next breeding cycle next week, they will meet for the first time outside and nature will be allowed to take its thunderous course.

The last black rhino birth in Pittsburgh was 30 years ago. If Azzizi and Jomo mate, a new rhino calf would be born in 15 to 16 months, possibly in January 2011. Rhino calves weigh between 70 and 100 pounds at birth. Adult black rhinos, which are actually gray, weight between 1,700 and 3,000 pounds.

Zoo officials and keepers have done everything possible short of Sinatra and chardonnay to make sure the tryst comes off without a hitch. They conducted blood tests that showed Azzizi is cycling regularly and had rhino experts from Berlin, Germany, do ultrasound testing to determine she is able to reproduce.

Because the mating can be rough, zoo keepers have begun giving Azzizi vitamin E shots to help alleviate any muscle soreness. Yesterday, a zoo keeper was filing down Azzizi's horns, which can be very sharp, to minimize the potential for injury to Jomo during courtship.

"It is tough to explain exactly what will be going on but we do know that during the mating ritual, their behavior is totally different from anything we have seen before or that our visitors have seen or heard," Dr. Baker said. "There will be zoo staff on hand to explain rhino behavior and we will block off areas around the rhino exhibit."

Zoo visitors wishing to view the rhino yard during the mating will be able to do so but from a greater distance than usual. Zoo officials will be on hand to alert parents with children.

There are 30 black rhinos in North American zoos and the Association of Zoos & Aquariums Species Survival Plan, which recommended the breeding in Pittsburgh, has set a target of four to seven births per year, a number needed to maintain a 3 percent birth rate, which would sustain the population. The goal is to grow the captive black rhino population to 72 rhinos. Black rhinos have a life span of 40 to 45 years in zoos.

There are five species of rhinos: the Sumatran, Javan, black, white and Indian. The black, Javan and white rhinos are considered critically endangered. Black rhinos, native to Africa, number about 4,240 in the wild. A global action plan to protect all rhinos is under development.

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