A Brookfield Zoo official on Thursday evening announced the birth of a second bottlenose dolphin within five days.
Sondra Katzen, with the Chicago Zoological Society, said a 27-year-old dolphin named Allie gave birth to a female calf early Tuesday.
Allie is a protective mother and was successfully nursing the calf and slipstreaming — when the calf rests in his mother's wake as she swims, Katzen said.
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The zoo also welcomed a male calf born to 9-year-old Allison on Dec. 12.
The society's marine mammal curator, Rita Stacey, said the births have been very rewarding for the marine mammal team. She has said a calf's first 30 days are critical, and a dolphin birth is not considered successful until the calf reaches 1 year old.
"We are thrilled with this birth, as well as with Allison’s calf," Stacey said.
The Chicago Zoological Society has cared for bottlenose dolphins for 54 years and opened the first inland oceanarium in the United States in 1961.