Mike McClure, the zoo's general curator and elephant manager, traveled last year to Riddle's Elephant Sanctuary and Wildlife Center in Arkansas for training in the management of elephant births.
Riddle's is where Felix, 24, retired after a career in show business. She and Tuffy - a 23-year-old male - lived there until they were brought to Baltimore to expand and diversify the Maryland Zoo's herd.
McClure and Felix both were present at Riddle's to witness a delivery. "She was very interested in the other elephant's calf - smelling it, touching it and investigating," McClure reported.
Felix's first calf was born five years ago at Riddle. "She was a very doting mother," McClure said. That calf was a male. Zoo officials know the new calf's gender, but they aren't saying.
Tuffy isn't the father. He has never been mated, although zoo officials said they hope he and Felix might hook up once her next calf is four or five years old.
Felix was already 19 months pregnant when she arrived with Tuffy. Her belly bulges a bit in front of her left hind leg, and her mammary glands - just two, between her front legs - are visibly swollen.
Her prenatal care has intensified here since her arrival.
Since early February, said senior zoo veterinarian Dr. Ellen Bronson, Felix's keepers have drawn blood from a vein behind her huge ear. Two tubes are taken daily and tested for signs of infection, kidney and liver function and, most of all, hormone levels.
"For the last month, we've been looking at progesterone," Bronson said. The hormone, produced by the ovaries and placenta, is vital to maintain a pregnancy, and to promote mammary development.
"Two to seven days before delivery, it drops to baseline, as if she were not pregnant," Bronson said. That's the signal to the body to begin the delivery process. So far, there has been little change. "We're sitting on pins and needles watching those numbers," Bronson said.
Samples are being sent daily for confirmation at Johns Hopkins Hospital, and twice weekly to the National Zoo's Conservation Research Center in Front Royal, Va.
Felix is also trained to accept ultrasound exams, every other day. One is performed rectally to check her cervix, which will start to dilate 12 to 24 hours before delivery. "Right now she's all tightly closed," at about 2 centimeters, Bronson said. In time, it will open wide enough ... well, for an elephant to pass through.
