Zoo Biologist Insists Storks are Cooler Than Pandas

Tom Jensen doesn’t hate pandas. He just thinks they are overrated. Although these charismatic bears attracted record crowds during their time at the San Diego Zoo, Jensen insists there are “cooler and prettier” black and white animals. 

As a senior scientist with the Zoo’s Wildlife Alliance, Jensen works with endangered species, and he’s particularly passionate about the birds that fly under the radar of most Zoo visitors. But being a bird biologist in a department where “nearly everyone else studies mammals” means Jensen’s lab must compete for visibility. “We’re like the little dog that has to yap louder,” he says. 

So far, Jensen’s dogged persistence has paid off. In his 22-year career, he’s developed many valuable techniques to benefit wildlife conservation.

Saving Storks One Egg at a Time

Like many of his projects, Jensen’s greatest success story originated during a conversation with zookeepers. The keepers managed the Zoo’s Storm’s storks, a large bird native to Indonesian swamplands. 

With fewer than 400 worldwide, Storm’s storks are more endangered than pandas. “They’re also black and white, plus a little red on the beak,” says Jensen. “So, they’re actually cooler than pandas — cooler and prettier. They’re better than pandas.”

After hatching five consecutive male storks, the keepers faced a heartbreaking dilemma. The territorial males must be housed separately, and the Zoo had limited space. Though they desperately needed additional females to continue their breeding program, the keepers were tossing out eggs for fear of hatching more males. They wondered if there was a way to identify the gender of the developing chicks before incubating them. 

Jensen knew a simple DNA blood test could provide the answer, but drawing blood from an embryo inside a brittle eggshell was no easy task. Determined to help, he modified a technique previously developed for cranes. Using a belt sander, Jensen scraped a small hole in the egg’s surface and carefully drew blood from the tiny vessels beneath the shell. Just 1/100 of a drop was enough blood to test the DNA. 

By the next breeding season, Jensen had perfected the technique, and he was thrilled when the Zoo hatched five female storks. “When you’re managing endangered species, every breeding season counts, every individual counts,” he says. 

The keepers soon asked Jensen to “do his magic” with other birds’ eggs. He has since applied this in ovosexing technique to more than 25 species, some with fragile eggs no bigger than a fingertip. 

Making Magic for Rhinos

Jensen’s fascination with birds began as a young boy in Denmark. Growing up on a farm with large aviaries, he quickly outgrew his initial interest in marine biology. Despite “never being that interested in mammals,” he enjoys collaborating with colleagues. “I’ve been trying to help with a lot of mammal things,” he says. 

Sometimes those “mammal things” put Jensen in awkward positions. For instance, two years ago, he helped his coworkers perform electroejaculations on a rhino. With two people holding up the sedated animal’s rear leg, Jensen crouched underneath the rhino’s rump to do the dirty deed.

“If you had told me in graduate school that I was going to be collecting semen from a rhino, I would have said, ‘Absolutely not.’ But there I was.” 

Apparently, Jensen had the magic touch. The semen he collected was used in the Zoo’s first successful artificial insemination of a southern white rhino. “I wasn’t involved in the insemination,” he says. “But I did get the sperm!” 

In addition to rhinos, Jensen conducts reproductive research with turtles, okapis, and even his nemesis the panda. His methodological repertoire includes behavioral studies, physiology, and genetics. In an era when scientists are increasingly specialized, Jensen purposefully pursues variety. “I get bored if I get too narrowed down,” he says.

Crushing It In and Out of the Lab

Jensen’s need for novelty extends to his hobbies. Already an experienced pilot and scuba diver, he recently picked up another pastime — assistant winemaker at a friend’s vineyard. He helps harvest, crush, and stem the grapes as well as monitor the alcohol and sugar levels during the aging process. 

His science background comes in handy, but not as much as you might think. “I mostly help make sure the calculations are correct,” he says. 

Winemaking involves a lot of trial and error, and that’s why Jensen enjoys it. “It’s nice because it’s so different from what I normally do in the lab.” 

But Jensen won’t be trading his eggshells for wine barrels anytime soon. He loves his work, even when it means sharing the spotlight with mammals. When he gives career talks at local schools, students always ask how much money he makes.

“That’s not what’s important,” he says. “What’s important is I get to stick my hand up a rhino’s rear end. I get to pet an okapi. I get to ultrasound a panda. Those are important.”

What’s most important to Jensen, however, is shining a spotlight on the zoo’s overshadowed animals. But overcoming mammalian bias isn’t easy when the cute and cuddly critters attract the crowds. “It used to be competing with the pandas, now it’s the rhinos,” he says.

While these charismatic creatures may bring people to the zoo, Jensen hopes visitors find beauty in some of the lesser-known animals, particularly one cooler and prettier black and white bird with a touch of red on its beak. 

To learn about some other unusual animals, check out this article.