Working with death, the Smithsonian National Zoo’s Kali Holder gathers lessons on life

When an animal becomes endangered, it is usually a bad thing, but not for the scimitar-horned oryx. Before the end of 2023, scimitar-horned oryxes were classified as “extinct in the wild,” teetering on the edge of total extinction. But through a sustained, international effort, their population grew and they were reclassified as “endangered,” making them the first animals to reach this status after nearly dying out. 

These antelope-like creatures’ only hope for long-term success is if zoos breed them and carefully reintroduce them to their native land. The Smithsonian National Zoo and Conservation Biology Institute supports this effort through the Chad Oryx Reintroduction Project. The first release, consisting of 23 individuals bred in captivity, began in 2016.  

But reintroducing species into the wild is not without its challenges. One oryx in the Zoo’s breeding program, Jenna, became pregnant in 2017 and the staff was optimistic that a brighter future for her species lay ahead. Her keepers watched closely as she brought her pregnancy to term. Everything was looking good—she was healthy and nothing seemed abnormal. But during labor, Jenna struggled. The calf got stuck and ultimately, instead of giving birth to a new calf, Jenna succumbed to irreversible complications and her team had no choice but to put her down. 

One of the National Zoo’s three veterinary pathologists, Kali Holder, found that Jenna experienced “dystocia,” a difficult birth caused in this case by a poorly positioned fetus. Studying Jenna, Holder learned there was nothing the oryx’s keepers could have done. “This sort of thing is almost impossible to prevent. It’s always a risk. It was absolutely heartbreaking. The whole point of having them in our care is to make sure their population grows. You can do everything right and still fail. This is one of the hardest lessons to learn.” 

Holder keeps Jenna’s skull, complete with her three-foot long set of horns, in her office as a reminder that we are just observers of nature and not able to control every variable. “It’s one of the cruelties in life. We’ll never be able to overcome the nature of nature,” she said. 

Jenna was Holder’s first big case. Since then, she has performed biopsies and necropsies (animal autopsies) on many of the animals that have died at the National Zoo and Conservation Biology Institute. Her goal is to learn as much about an animal’s body as she can. “As a conservation pathologist, I gather as much information as possible about the health of our animals—not just the cause of death (because we often know the cause of death), but I'm also going to be able to tell you everything we can glean from that last moment. How was that animal's health over the course of its life? What was its nutritional status? Did it harbor any parasites or infectious diseases? If we find the animal carried something infectious, how might this affect animals it was in contact with, its keepers, and our collections?” 

Holder says the most important aspect of her work is applying what she learns to situations well beyond the laboratory. “Knowing what species are prone to which health issues helps us figure out how to manage animal care at the Zoo and in the wild,” she said. 

Occasionally, a specific animal taps into Holder’s emotions, namely difficult cases like Jenna’s or an animal she knew when it was alive. But in most cases, Holder doesn’t meet the animal until it arrives in her lab, which allows her to focus on the challenge of gathering clues about the animal’s life. 

“It’s a mystery. It’s problem solving. I’m driven by a burning curiosity to see what’s happening in my cases, and postmortem analysis is one of the ways we get to learn. I find it all fascinating, especially when I just get into the weeds. Nature is so much weirder than anything you can intentionally make up.”  

Holder not only loves what she does; she also enjoys talking about it. She approaches her area of work—an area that might make some people uncomfortable—with professionalism, confidence, and humor. She helps run Nerd Nite DC, and she loves finding ways to connect pop culture with actual science. Holder introduced her fascination with animals to a broader audience when she appeared on NPR’s Science Friday radio show.  

She also participated in the 500 Queer Scientists campaign to show the world that it is possible to be both a scientist and an openly queer woman. “One of the things I'm grateful for is that I get to provide my perspective and raise my voice and say, ‘You know what, there are scientists who are queer. It's not going to stop you from being a scientist.’ We are out here. We are doing good work. We like to talk about our science. It’s important to show that all scientists don't live one way. We need more voices. There are so many more ways to be human, which means there are so many ways to do science.” 

It might be hard to imagine how someone could stay so positive and joyful while working with zoo animals that have passed on. But Holder says it makes sense. “The animal’s life has been bookended, and now it's my job to turn that life into information so that the animal's life continues to have an impact beyond its end. I'm trying to get as much info as possible so we can apply those lessons to our care going forward.”