CHICAGO (CBS) — A female baby dolphin calf born just last week has died. The zoo confirms the death of the bottlenose dolphin, who was the offspring of 26-year-old and Brookfield Zoo resident Allie.

The little calf wasn’t nursing overnight and quickly declined. Zoo vets tried treating her and even performed CPR, but she could not be saved.

Doctor Michael Adkesson Vice President of Clinical Medicine at Brookfield Zoo, tells WBBM the first 30 days of a dolphin calf’s life are a critical and often difficult phase.

“As we were watching, we started seeing this weakness developing in the calf that would be associated with it just not being able to take in the nourishment or nurse the way that we would like to be seeing and that is probably been building for the immediate period leading up to the calf becoming weak,” said Adkesson.

A necropsy will be performed to find the cause of her death. The public never got a look at the newborn dolphin.

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