The zoo staff had closely monitored the 29-year-old dolphin mother named Tapeko during her pregnancy. Everything appeared to be normal, but immediately after the calf was born Sunday morning, the staff knew it was in trouble. A healthy calf would swim to the surface and take a breath but Tapeko's newborn was weak and could not do that.
"Tapeko tried her best to sort of nudge it to the surface and was successful in getting it up there but the calf was not able to take that breath and really do well from the beginning, so we knew right away that something was wrong," said Dr. Michael Adkesson, brookfield zoo.
A necropsy -- or animal autopsy -- was performed Sunday but the initial tests did not find a cause of death.
The zoo cancelled Sunday's dolphin presentations and closed the underwater viewing. Adkesson says the mother Tapeko is doing well.