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Saving Rhinos
Although most people think “Africa” when they hear “rhino” Asian rhinos are more endangered than the African species. In the past, CREW scientists focused on two of these Asian species, the Sumatran rhino and greater one-horned (GOH) rhino. They succeeded in unraveling the mysteries of breeding Sumatran rhinos in managed care while developing artificial insemination for producing genetically valuable GOH rhino calves. However, the landscape has changed, and the deadly poaching epidemic that started in Africa in 2008 now imperils all rhino species. Therefore, CREW’s conservation research efforts are increasingly important for ensuring that all rhinos thrive, including those in our zoos. Our most recent project – the American Institute of Rhinoceros Science (AIRS) is a bold initiative aimed at doing exactly that.
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CREW scientists have been instrumental in increasing the number of Sumatran rhinos. -
Sumatran Rhino "Harapan" was one of three born at the Cincinnati Zoo -
American Institute of Rhinoceros Science (AIRS)
CREW is partnering with The Wilds, Disney’s Animals, Science and Environment, George Mason University, the South-East Zoo Alliance for Reproduction & Conservation, and Stellenbosch University, South Africa, on a new, big initiative, taking rhino science and collaboration to a new level while helping to save rhinos from extinction.
AIRS is led by a coalition of expert rhino scientists. This large coalition is employing a multidisciplinary, integrative strategy to overcome the four greatest scientific challenges to sustaining rhino populations within our nation’s zoos. The team recognizes that the scientific challenges are inter-related, and studying one of them in isolation will fall short of what could be achieved by tackling all of them together. In short, the whole is greater than the sum of its parts.
AIRS consists of a diverse, inclusive team of scientists in all stages of their training/careers. The project’s goal is to produce science-based, affordable, and feasible management recommendations for monitoring and controlling physical condition, iron overload, and reproduction while ensuring optimal rhino wellbeing. (AIRS is supported by a grant from the Institute of Museum and Library Services #MG 249011-OMS-21.)
Health and physical fitness are intrinsically linked in wildlife species just as they are in humans, but we really don’t know how to accurately assess the fitness of rhinos. AIRS scientists tested many methods in conjunction with blood sample collections so that biomarkers of health could be paired with fitness assessment results. Data analysis is complicated and underway, but what we know so far includes:
- The rhino activity tracker (think about your fitness watch!) is very well tolerated by rhinos and provides valuable insight into rhino activity throughout the day/night (PLOS One in review).
- Most rhinos in human care are over-conditioned – i.e., they are heavier and less fit than they probably should be.
- Most black and white rhinos are active for less than 20% of each 24 h period, taking an average of 15,000 and 8,000 steps/day, respectively! Black rhino activity does not vary much by season, but white rhinos in the northern-most climates are less active in winter compared to summer taking 3000 fewer steps in that season.
- Based on the medical survey, the rhino population appears to be in good health with only a minority of rhinos experiencing recurring or chronic health conditions.
Historically, fewer than half of the female white rhinos in our zoos reproduced successfully. Potential causes for reproductive failure include stress, social preferences or pressures, genetics, health and nutrition. A deeper dive into rhino reproduction by AIRS scientists has revealed the following:
White rhino reproduction has improved from ~40% to >60% of female rhinos successfully producing at least one calf (Therio Wild). Over 30% of female white rhinos in AIRS were even pregnant during the study period!- Sharing space with a novel, mature breeding bull can be a strong stimulus of ovarian activity in female white rhinos, proving social influences and management practices allowing such interactions are important in breeding efforts (Therio Wild).
- Dysfunctional prolactin production does not appear responsible for reproductive failure in white rhinos (Therio Wild in review), but it may provide a new diagnostic biomarker of pregnancy (Therio Wild).
- Artificial insemination (AI) could help the small portion of female rhinos that still won’t breed naturally, and sperm quality is important for AI success, so AIRS established a standardized computer-assisted, field-friendly method for sperm evaluation (Therio Wild).
Physical health is important, but so is psychological wellbeing, and we want the best of both for animals in our zoos. However, assessing rhino wellbeing beyond the physical health component can be very challenging. AIRS scientists mapped behavior, social dynamics, temperament, and space use alongside serum biomarkers and management characteristics, with the goal of translating these measures into clear, trackable indicators of wellbeing that could inform everyday rhino management practices. Early findings do just that.
Rhino temperaments are complex and affect how rhinos interact with novel objects in their enclosure; therefore, temperament should be considered when providing various forms of enrichment and when considering adjustments to enclosure design to enhance individual wellbeing (PLOS One).- Ensuring ample opportunities for social interactions among both black and white rhinos is important for optimal rhino care since both species exhibit increased affiliative behaviors when social settings allow for close conspecific interactions. White rhinos also had lower concentrations of a biomarker associated with DNA damage when housed in large groups and large habitats.
- Interpretation of serum cortisol:DHEA ratio versus cortisol alone can lead to different conclusions, which reinforces the prevailing theory that cortisol:DHEA is a more accurate indicator when assessing individual wellbeing (Gen & Comp Endo in review).
- Biomarkers of wellbeing have cross-disciplinary value: DHEA appears to increase throughout healthy pregnancies (Cons Phys), and oxytocin increases during the first year of successful lactation (Therio Wild). A biomarker of DNA damage was associated with clinical and behavioral pathologies in black rhinos and will be explored further for relationships to physical health.
Iron overload disorder (IOD) primarily afflicts black rhinos and Sumatran rhinos. It is characterized by high concentrations of iron stored in organ tissues (liver and spleen) that could have health implications. Unfortunately, typical serum biomarkers for monitoring IOD have proven unreliable in rhinos. AIRS scientists have studied many aspects of IOD and key findings are below.
There are many measurable minerals in rhino horn (Scientific Reports), but only arsenic and selenium concentrations (not iron) are correlated to those in rhino liver (PLOS One).- Low horn mineral concentrations documented in our studies refute theories that rhino horn is effective in treating a variety of human ailments (Mongabay).
- Several minerals are elevated in liver tissues of zoo rhinos compared to wild counterparts including iron, molybdenum, lead (black rhinos) and copper, iron, molybdenum (white rhinos). The potential impacts of all of them warrant more attention in rhino health studies (paper in review).
- IOD impacts black and Sumatran rhinos differently – only Sumatran rhinos have experienced liver failure due to high iron loads (JZWM paper), whereas black rhinos with even higher liver iron concentrations do not exhibit serious liver pathology.
Sumatran Rhino Breeding Program at the Cincinnati Zoo
After years of research, scientists at Cincinnati Zoo’s Center for Conservation and Research of Endangered Wildlife (CREW), led by Dr. Terri Roth, unraveled the mysteries of Sumatran rhino reproduction and, in 2001, Andalas was born. He was the first calf bred and born in any zoo in the world in 112 years. In 2004, his sister, Suci, was born, and in 2007, Harapan arrived. Between 2001 and 2012, the Cincinnati Zoo held the distinction as the only place successfully breeding this endangered species. The Zoo partnered with Indonesian and Malaysian colleagues to transfer knowledge and techniques so that they too could succeed. In 2007, the Cincinnati and Los Angeles Zoos agreed to send Andalas to the Sumatran Rhino Sanctuary (SRS). That sacrifice on the part of the LA Zoo, where Andalas was living at the time of his transfer, paid off in spades in 2012 when Andalas’ healthy son was born in Sumatra.
Since then, Andalas has sired 3 calves born in 2012, 2016 and 2023 (one male and two daughters). His elder two have now produced calves, and Harapan is the father of the one born on November 25, 2023.
The Cincinnati Zoo works closely with the Indonesian Ministry of Forestry, the Indonesian Rhino Foundation, the IUCN Asian Rhino Specialist Group and the International Rhino Foundation, to protect this species in the wild and also propagate Sumatran rhinos in zoos.
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Andalas - Born Sept. 13, 2001 -
Suci -
Harapan in Cincinnati -
Paul Rinehart in Sumatra with Harapan in 2015 -
Ipuh and Emi -
Ratu and her calf, Andatu, at the Sumatran Rhino Sanctuary. -
Delilah