Why Animals Die Prematurely in Zoos

It’s sad, but it happens. And it’s not always out of ignorance.

Dec 1 2014, 7:45pm

​One of Como Park Zoo's gorillas. Image: ​Garrett Voight/Flickr

Last Monday, the Como Park Zoo and Conservatory in St. Paul, Minnesota announced that its five-day-old baby gorilla had died. This was the first baby to be born at the zoo since it started caring for gorillas over 50 years ago. Zookeepers were monitoring the pair closely since the baby's birth, but in an attempt to let the first-time mother bond with her baby, they didn't intervene when they lost track of how much the baby was being fed.

"Despite best efforts to monitor and record the baby's food intake, many times Alice [the mother] would cradle her baby to her chest with her back towards the observing zookeepers making it difficult to determine when, and if, nursing was indeed taking place," the zoo said in a statement. Senior zookeeper Allison Jungheim told Minnesota Public Radio that both the zoo staff and the gorillas themselves were mourning the loss, which has initially been blamed on nutrition complications, pending an autopsy.

Animals in zoos are supposed to be getting the best care available in the name of conservation, but accidental deaths, like that of Como Park's infant gorilla, do happen. Is this just a price of running a zoo, or can those deaths be stopped?

It's not clear how many accidental animal deaths that occur in zoos each year, as studies on zoo mortality generally rely on non-comprehensive and species-specific data sets in the hopes of improving care. (I called the Association of Zoos and Aquariums after being told they may have solid figures, but I haven't heard back.) A number of factors can make the deaths more or less likely, such as the type of institution (do guests walk through or drive through?), the zoo's size, and the number of staff members.

Chris Draper, programmes manager of captive wild animals with the Born Free Foundation, a British non-profit, said that sometimes the factors are within the zoo's control, like if the animal's enclosure is below the public viewing area, which means people are more likely to drop objects into it that may injure or kill the animal. But other times a fire or a flood affect the zoo, and there's not much zookeepers can do about it.

"Responsible facilities would do their best to absolutely minimize these things," Draper said. "With less responsible facilities, if fires happen for example, you can't prevent every case but you should at least have advanced warning [to move the animals to safety]."

On some level, accidental deaths in zoos are inevitable. "We live in a risk management world," said Bob Cisneros, the President of the American Association of Zoo Keepers and a keeper for over 20 years. "While incidents and accidents happen [at zoos], stopgap measures are put into place to minimize risk."

Zookeepers are tasked with monitoring, feeding, and caring for several animals at once, making sure something doesn't seem off about them. But depending on the circumstances, intervening may not be the best plan of action.

"There's always a judgment call about when to intervene," Draper said, especially when it comes to mothers that are bonding with their offspring. The fear is that the offspring will be imprinted (attach to and learn specific behaviors) by humans and not by a member of its own species.

There's always a judgment call about when to intervene

"Hand-raised animals do not make good parents," Cisneros said. "The bond that exists between a [mother] and its offspring is incredibly important because that offspring is taught some amazing behaviors that carry over into parenthood."

When ape mothers have given birth in captivity and have cared for their offspring themselves, Cisneros said, both the mother and the baby benefit. "Statistically this produces an offspring that is geared to develop into a parent at a later stage, and [zookeepers] produce a steady cycle of good parenting," he added. "When we intervene, we offset that balance."

The situation is less delicate with animals that don't bond to their young, like fish or insects. But any zoologist will tell you that there's still a lot we don't know about animals, so we don't know what kind of impact a zookeeper's intervention could have. "People don't have a full picture of every nuance of what [animals] would naturally do in the wild," Draper said. "A lot of what they're doing in zookeeping is guesswork, sometimes based on mythology."

In his two decades as a zookeeper, Cisneros said he used more evidence-based observation than Draper insinuated. It's possible to check on an animal's well-being more efficiently than ever, through weigh-ins, blood samples and fecal samples. Designated nutritionists carefully plan animals' diets, and zoo managers and executives share the outcomes across institutions, Cisneros said. "But there are animals we know lots about and there are animals we're still trying to understand as much as we can," he added.

Pittsburgh Zoo's Moka, with infant. Image: ​Sage Ross/Flickr

Even though accidental deaths do happen, animals in captivity generally have a lower mortality rate than they would in the wild. The Como Park Zoo says that 26 percent of male gorillas and 20 percent of female gorillas die within the first year when born in captivity; in the wild, that mortality rate varies, with one recent PLOS One study finding an infant mortality ​of around 26 percent in one gorilla population.

But Draper questions the idea that zoos are actually beneficial for conservation. "Other than refining how we keep animals captive, we should acknowledge that keeping them captive comes with risks to their safety and healthcare," he said.

Many organizations that breed endangered animals in captivity, including gorillas, justify this with plans to reintroduce the species to their native habitat. But Draper pointed out that not only have zoologists struggled to reintroduce species in the past, the species may not have a habitat to go back to at all.

"Even if there was some benefit, I don't think it outweighs the problem that animals themselves face," Draper said.

But Cisneros said that zoos are instrumental to conservation by engaging people with the animals housed there. "My job as a zookeeper is to connect [visitors] to animals in a new way so that when you watch National Geographic or Animal Planet, you have a stronger connection because you've smelled the popcorn smell of a binturong or you were able to feel the softness of a miniature horse," he said. "We get people connected to saving species in a world we have a lot of habitat loss and species extinction."

Both Cisneros and Draper noted that animal welfare is the biggest concern in zoos today. There's a lot to learn about the animals that keepers are already caring for, but higher-ups need to ensure the keepers have all the known information available to them.

"It's a good debate because people are talking about animal welfare," Cisneros said. "As a result of discussions, there are great changes going on."

The death of Como Park Zoo's baby gorilla is a tragedy by most definitions, but it wasn't because of negligence or ignorance—it's because keepers understand that, for both mother and baby gorillas, it's usually better for them to bond naturally without human intervention. Unfortunately, this time the outcome wasn't a positive one.