Making Babies!

Zoo InternQuest is a seven-week career exploration program for San Diego County high school juniors and seniors. Students have the unique opportunity to meet professionals working for the San Diego Zoo, Safari Park, and Institute for Conservation Research, learn about their jobs, and then blog about their experience online. Follow their adventures here on the Zoo’s website!


Mr. Tubbs and Mrs. Felton Felton who both work in the Reproductive Sciences department at San Diego Zoo Global. These two work to assist the reproduction of endangered species.

Mr. Tubbs, Associate Director, and Mrs. Felton Felton, Research Coordinator, both work in the Reproductive Sciences Team at the San Diego Zoo Global Institute for Conservation Research (ICR). They work in an endocrine lab where they monitor hormones to help animals have optimal conditions for reproduction. By tracking hormones such as progesterone, they are able to determine when a female is in estrus (fertile) and monitor pregnancy. Since hormone levels must be checked often for accurate data, Mr. Tubbs and Mrs. Felton must obtain samples from the animals regularly. Though blood samples are the best way to track hormones, it is not ideal to draw blood from the animals multiple times a week, as multiple blood draws aren’t always feasible. For this reason, Mr. Tubbs and Mrs. Felton frequently use fecal and urine samples to track hormones. Mr. Tubbs and Mrs. Felton also look for genes of interest in tissue samples, especially those that code for cell receptors which aid in reproduction. Their work helps in the conservation of species, as reproduction allows for them to survive and thrive. Both Mr. Tubbs and Mrs. Felton have aided in the successful conservation efforts of rhinoceros and the California condor. They plan to begin new conservation research on big cats soon.  


The endocrine lab where Mr. Tubbs and Mrs. Felton conduct their research. An example of one of the hormones they test for is progesterone, that is involved in the female reproductive system. By studying this hormone, Mr. Tubbs and Mrs. Felton are able to determine whether a female is ovulating, pregnant, has had a miscarriage, or any other related information.

Mr. Tubbs and Mrs. Felton didn’t always know they wanted to work in the research field. Before the ICR, Mr. Tubbs studied at the University of Florida and got his PhD at Texas State. Originally, Mr. Tubbs wanted to be a veterinarian, until his biology professor inspired him with tales of his own experiences in research. Both began on a path to becoming veterinarians before finding jobs with the ICR. Mrs. Felton began her studies at San Diego State University. She found her appreciation for research when she began studying at Missouri State and became a maned wolf keeper at the Missouri Zoo. Both of their most memorable experiences at the ICR include working with the native California condors and the endangered white rhinos. Mr. Tubbs and Mrs. Felton carry out their love for conservation in their personal life. Mr. Tubbs likes spending time outdoors with his family, and Mrs. Felton enjoys riding her horse, cleaning up the environment, and educating others about conservation.


Zoo InternQuest students analyze progesterone levels and make conclusions on the hormonal condition of different female animals. Progesterone is a sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis.

As endocrinologists, Mr. Tubbs and Mrs. Felton work with all kinds of animals, not just rhinos and condors. Endocrinologists study the glands that produce hormones and hormones themselves. In their department, they study animal tissues, feces and all other kinds of samples. They have studied southern white rhinos, polar bears, zebras and condors to name a few. They have also done some interesting research on the link between diet and fertility, working with female snow leopards, Sumatran tigers, and most of all, the southern white rhino. Mr. Tubbs and Mrs. Felton were studying diet because many female rhinos in managed care are less likely to give birth than their wild counterparts. They discovered that the pellet diet of rhinos, made with soy and alfalfa, contained phytoestrogens. These compounds suppress rhinoceros reproduction by upsetting the balance of their hormones, disrupting ovulation. Mr. Tubbs and Mrs. Felton’s important findings led to the ICR reworking its nutritional plans, and multiple zoos have followed suit. The ICR now gives its rhinos pellets that have been redesigned to mimic the wild diet while still providing the rhinos with important nutrients and little to no phytoestrogens.

Mr. Tubbs is an avid conservationist and strives to end extinction. The way he fights extinction is also his best conservation-related accomplishment: making babies! His main focus is to trigger an upsurge in the populations of endangered animal species. By altering the diet being fed to the southern white rhinos at the facility, the amount of rhino babies born has increased. Mrs. Felton and Mr. Tubbs watch over their southern white rhinos carefully, by retrieving tissue and monitoring their hormones. Participating in the rhino diet project is another one of his accomplishments. Working at the ICR is not the only way to help conserve animals. By supporting organizations that focus aid on wildlife conservation such as The International Rhino Fund you can help rhino conservation from afar. You can also help the environment as a whole, by doing simple environmental deeds. For example, beach and canyon cleanups create a dent in the amount of trash entering waterways. Donating to organizations such as San Diego Zoo Global or WWF (World Wildlife Fund), volunteering to clean up our environment, and educating the public on endangered species are all great ways to do your part in protecting wildlife around the globe.


Mr. Tubbs showing the interns frozen feces samples. The one he is holding is actually an okapi sample! Testing feces is an alternative way of collecting data on the hormonal status of an animal, rather than collecting samples directly from the animal through procedures, etc.

Mrs. Felton realized what kind of work she wanted to do when she first partook in experiments that dealt with analyzing hormones in a maned wolf’s excrement. To distinguish between two individuals, one would be fed glitter and the other would not. This kind of work fascinated her. Those who seek Mrs. Felton’s job have to be able to take something that the world usually views as “disgusting” and see it as an opportunity for answers. They also have to know that although the job’s purpose is to help animals, most of the time will be spent in the lab. Mrs. Felton also recommends seeking out opportunities like she did, such as taking internships or part-time jobs for zoo keeping. Earning her Bachelor’s Degree in Biology and her Master’s Degree in Animal Science enabled her to do the work she is passionate about; that is, work that upholds the environment and its species. If you’re interested in contributing to the efforts of this field, Mr. Tubbs also recommends finding hobbies and occupations you are passionate about.


The interns, Mr. Tubbs and Mrs. Felton! All of us are actually posing in front of the refrigerators where the feces samples are kept in the endocrine lab.

A major part of Mr. Tubbs’ job is to study both natural and assisted reproduction for a variety of animals. One of his favorite experiences was when he stayed at the Kruger National Park in South Africa to study wild white rhino diets and their impact on fertility. The most rewarding part of his job is being able to see baby white rhinos born in managed care, thanks in large part to his team’s conservation efforts and research. Although Mr. Tubbs enjoys working with rhinos, he has always considered his favorite animals to be fish, because he loves fishing and being out in nature with his family. Mrs. Felton’s favorite animal is the okapi but they have a particularly hard time breeding in managed care. Mrs. Felton is able to research them as well as other species that are highly endangered such as white rhinos and condors. One of her favorite memories was when was she tested wild condors’ blood to see the amount of lead they had in their body. Lead ammunition used in hunting can contaminate the carcass, which poisons the condors that scavenge the area. This killed off a majority of the condor population until there were only 22 left in the wild. With the help of San Diego Zoo Global, and people like Mr. Tubbs and Mrs. Felton, the condor population has grown to over 450 individuals. 


This is the Frozen Zoo, a storage facility in which genetic materials taken from animals are stored at very low temperatures in liquid nitrogen. The freezing of samples is species specific, meaning that every animal’s tissues are different and need to be preserved in different ways.

The ICR is a critical piece of San Diego Zoo Global’s conservation mission, where numerous breakthroughs in the reproductive sciences have been made. Mr. Tubbs and Mrs. Felton work to preserve and promote the fertility of the animals in the Zoo’s care. Their research has been highly influential in helping the southern white rhinos and California condors. As interns, we were lucky enough to be able to ask them about their work and the path that led them here. It was a pleasure talking to them both, and we hope that you enjoyed learning about their jobs as much as we did.

Week One
Fall Session 2019