The Cincinnati Zoo and Botanical Garden revealed that one of their hippopotamuses, 23-year-old Bibi, gave birth to an unexpected calf despite being on birth control.
This was not the first “surprise” birth at the Cincinnati Zoo. Just one year ago, in 2021, the zoo announced the birth of an unplanned baby wallaby to mother Ava. This unplanned birth immediately followed Ava’s birth of a baby named Pocket in May of the previous year. According to zoo officials, the pregnancy came as a shock. Zoo staff attributed this surprise birth to embryonic diapause, or the temporary suspension of development of the embryo, which enables wallabies to carry multiple fertilized embryos at one time. What is a biological advantage in the wild that enhances the chance of successful reproduction and thus increased fitness, however, quickly becomes a disadvantage in a captive setting, where spatial and social resources are drastically limited and cannot support the addition of unplanned joeys that a natural ecosystem would.
Accidental Births at Zoos Are Common
These accounts join the dozens of other accidental births from zoos across the country, including:
- In 2017, a family of silvered leaf langurs, including male Walter, female Teagan, and Teagan’s daughter Melody, arrived at the Knoxville Zoo in December from the Santa Ana Zoo in California. One morning, zoo staff unexpectedly discovered that Teagan had given birth. She was not known to be pregnant by the zoo.
- In 2018, Eloise, a 37-year-old siamang at the San Diego Zoo, had been on birth control for several years, but in November, she gave birth to her seventh baby. The zoo stated that Eloise never exhibited any signs of pregnancy, and it remains unclear why the birth control was ineffective. Animal Care Manager Jill Andrews stated that the zoo was overjoyed; any birth involving an endangered species was a reason to celebrate.
- In 2021, Emma, a 16-year-old giraffe kept at the Dickerson Park Zoo, was discovered to be pregnant. According to her keepers, this pregnancy was extremely high risk, as conception occurred while she was receiving birth control treatments. To deliver the baby, performing a C-section under anesthesia was postulated to be the only way to conduct a successful birth, which carries its own life-threatening risks. According to Dr. Stephanie Zec, Dickerson Park Zoo’s Veterinarian, “We’re not sure exactly how this happened…It could be a number of things. Giraffe skin is one of the thickest of all mammals. Because of that the injection could have been given in the skin and not the muscle… [or] maybe [the solution] wasn’t mixed up enough. There’s all sorts of possibilities.” Emma previously had three healthy births and one calf born with health issues, who passed away shortly after birth. Apparently, no one noticed Emma was pregnant for approximately one year, despite the mating of giraffes being closely monitored by the Association of Zoos & Aquariums (AZA) Species Survival Program (SSP).
“Surprise” Babies Are Not Conservation Wins
As indicated by the case studies above, “surprise births” at zoos are not a species-specific or localized problem. Yes, birth control is not 100% effective, but zoos framing these contraceptive accidents as positive events for the species is grossly misleading to the public. To be clear, these are not happy accidents; the animals resulting from these births will never be released into the wild. The enclosure space they will be contained in is finite. These captive “miracle births” bring zoo breeding programs under scrutiny. Most zoos argue that they carefully manage the animals’ breeding and reproduction to improve their conservation status in the wild. While more animals—specifically more babies—bring more visitors and thus more money to zoos, zoos contribute little to none of the profits gained from admission tickets to impactful conservation efforts. Further, adding more animals, especially to enclosures already much too small, decreases these animals’ already poor welfare provision, which can be worsened further still by removing a baby from the mother to play musical chairs with other zoos looking for a new attraction to continue this perpetual cycle.
For these reasons, we ask that you join us in fighting against the keeping and breeding of wild animals (both intentionally and unintentionally) in captivity by choosing not to support zoos. “Excess” animals would not exist in captivity had they not been kept and propagated by zoos in the first place. You can read more about our plan to eventually phase-out wide-ranging species like elephants from zoos by halting future breeding in our report, A Legacy of Shame.
Keep Wildlife in the Wild,
Devan
