SAN DIEGO — In the dark, early hours of Monday morning, a male African elephant calf was born at the San Diego Zoo’s Safari Park. No human was there to witness it, but when the elephant staff arrived about 6 a.m., zoo staff noticed the tiny, new member of the African elephant herd. The sighting prompted keepers to call the mother, Litsemba, into an upper yard for a visual check of her and the new calf. When the Safari Park opened Monday, guests saw the unnamed calf walking, stumbling, exploring a puddle of water, nursing and lying down for a nap. The zoo’s animal-care staff were expecting Litsemba and her two calves to return to the main exhibit Tuesday. The newborn calf is the fourth male African elephant calf born at the park in 2010, which is the most elephant births the park has ever had in a single year. There are a total of 17 African elephants at the park — eight adults and nine calves. An adult African elephant is much larger than its cousin, the Asian elephant. A male African elephant weighs seven to eight tons and can stand more than 10 feet tall at the shoulders, according too zoo experts. A female can weigh about four tons and stand more than eight feet at the shoulders.