No birth control is 100 percent effective – and that's true even for hippopotamuses.
Veterinarians at the Los Angeles Zoo were reminded of this recently, when they realized the zoo's female hippo was pregnant, despite the fact that she was on birth control.
"Probably about two or three weeks ago, we started seeing such a significant weight gain, and a little bit of a change of attitude, that we surmised that she was probably pregnant, despite the birth control she was given," says Mike Maxcy, the zoo's principal animal keeper.
The mother, 10-year-old Mara, came to the zoo in December from Topeka. She was intended to be a companion for a male hippo, 3-year-old Adhama, who arrived from the San Diego Zoo last year.
The two animals hit it off immediately, Maxcy says.
"You could say they fell in love almost instantly – love at first sight," he says.
But the zoo wasn't prepared for hippo babies. Hippos are high-maintenance animals, requiring lots of space and food, Maxcy says.
So Mara was put on birth control – the Depo-Provera shot, to be exact. Veterinarians used a dart gun to inject her once a month, Maxcy says. But something went wrong.
"Just like human birth control, sometimes it doesn't always work," Maxcy says. He adds: "Sometimes animals that have a lot of fat deposits – that are heavy bodied – it’s not 100 percent."
The baby hippo was born on Halloween — the zoo's first hippo birth in 26 years. Maxcy says the baby hippo is about the size of a pot-bellied pig and estimates it weighs between 50 and 80 pounds.
But the zoo hasn't been able to weigh it yet, or even determine its sex, because right now, "the baby and the mom are inseparable," Maxcy says. "So we couldn't go into the exhibit and just pick up the baby because the mom would eat us."
Mara will nurse her baby for about a year, and the young hippo will be completely weaned off its mother's milk when it’s about 18 months old.
The zoo will keep the baby hippo for at least two or three years, before deciding whether it will need to be moved to another home, Maxcy says.