(CBS) – There’s a new addition at the Brookfield Zoo: a baby male dolphin.

The calf was born Wednesday to mother Tapeko and is about 40 pounds and 3.5 feet long.

The calf and mom are bonding and are off-exhibit, though the Seven Seas underwater viewing gallery remains open. Zoo officials say they are watching to make sure the baby dolphin hits certain “milestones,” such as nursing and “slipstreaming” – when the calf’s motion is helped along by the parent’s wake. The first month is particularly important.

“We know that the first 30 days are extremely critical in the calf’s life,” said Rita Stacey, marine mammal curator for the Chicago Zoological Society.

Tapeko is an experienced mother and successfully reared four calves.