A week-old bottlenose dolphin calf has died at Brookfield Zoo Chicago. The calf was born on Wednesday, Sept. 9, to Allison, a 20-year-old dolphin. The calf died Wednesday, Sept. 16, after “rapidly declining” early that morning.
A release from the zoo on Sept. 16 described the life of the male calf, from the morning of its birth before Allison went into labor through its death one week later. In the release, the zoo said Allison’s maternal care was “not yet consistent,” possibly due to her inexperience as a mother, describing that she allowed the calf to swim further from her than may have been ideal.
“While Allison demonstrated some of the maternal behaviors required to help her calf thrive, ultimately, they were not consistent or enough to sustain the calf’s needs,” said Dr. Rita Stacey-Vondra, the zoo’s senior vice president of programs and impact, in the written statement.
Initial assessments showed “some positive maternal behaviors,” according to the zoo, but Allison “struggled with other maternal care” that would have facilitated the calf’s reaching “critical developmental milestones.”
A full necropsy is underway, the zoo said. The results have not yet been released.
Allison’s calf is the second dolphin calf that has died in the past two years at Brookfield Zoo Chicago. In June 2025, a four-day-old calf died suddenly after its birth to Allie, a 38-year-old bottlenose dolphin.
The calf was meeting its expected milestones before zoo staff “witnessed a rapid, unexpected change in the calf’s behavior” just minutes before its death, the zoo said in a written release at the time.
This isn’t the first time Allison has lost a calf, either. On Dec. 12, 2014, 9-year-old Allison gave birth to a calf that also died at one week of age. According to a Zoo release published in the Landmark, Allison and her calf “began showing concerning behavioral changes in their swimming patterns” just a couple of days after its birth.
Veterinary staff intervened on the calf’s seventh day of life when “increasing problems” became apparent, but the calf died late on the evening of Dec. 19, 2014.
Bill Zeigler, then the senior vice president of collections and animal care for the Chicago Zoological Society, said zoo staff were hoping to allow Allison “the chance to gain maternal experience, which is learned,” as a first-time mother before deciding to intervene.
