"Ultrasound is a fantastic tool for us," says Jeff Boehm, senior vice president of animal health and conservation science. "We can get extraordinary images of the tail flukes, spine, ribs and head. We can get a heart rate of the developing calf." In addition to being able to track the fetus' growth — at this point it is about 2 feet long and 1 foot wide — Shedd's animal healthcare staffers can compare its measurements to those of previous calves to better pinpoint its stage of development.

Belugas have a gestation period of 14 to 16 months, so the calf is due in summer or early fall.

Mauyak is the mother of Qannik, who will be 7 in July. The new calf's father is Naluark, Shedd's sole adult male, who also sired Bella.

Shedd is one of nine North American aquariums and zoos committed to the public display and breeding of beluga whales. Ken Ramirez, vice president of animal collections and training, notes that Shedd's whale population is very dynamic, with Bella, a calf born in July 2006, pregnant Mauyak, and another female, Naya, paired with Naluark for the late winter/early spring breeding season.

The whales have rather public sex lives, which can be edifying for Shedd's guests but, more important, instructive for the other belugas, especially the younger ones. "Whales are observational learners," says Ken. "All the animals watch and learn from the process. Kayavak [born at Shedd in 1999] watched Qannik and Bella being born."

Bella's education has already begun. Her mom, Puiji, and her other constant companion in Secluded Bay, Naya, have both been consorting with Naluark. Says Ramirez, "We want to make sure that our whales experience the full range of normal social interactions, including breeding, the same as they would in the wild."