What Happens When Feral Horses Use Contraception? with Dr. Cassandra Nunez
- Marika
- 2 days ago
- 3 min read
Updated: 2 days ago
I sat down with Dr. Cassandra Nunez, an assistant research professor at the University of Memphis, to delve into the complex world of feral horses and the impact of human intervention on their populations. With her extensive research background on the feral horses of Shackleford Banks, Dr. Nunez provides insights into how contraception management affects their behavior and physiology.
Introduction to Feral Horse Research
Dr. Cassandra Nunez has dedicated years of her career to studying the behavior of feral horses. Being thoroughly acquainted with the Shackleford Banks horses during her PhD, she was uniquely positioned to investigate the behavioral changes noticed by the National Park Service when they introduced contraceptive management. This intervention aimed to control the horse population to protect the island's endangered plants and animals that were being impacted by overgrazing.
Contraception and Behavioral Observations
The introduction of contraception was driven by the need to balance the ecological impact the horses had on the environment due to a lack of natural predators. Dr. Nunez recalls how the park service initiated contraception when horse numbers approached unsustainable levels. Her groundbreaking study revealed significant behavioral changes in the horses—particularly the females—impacted by contraception. Notably, treated females displayed increased promiscuity, often changing bands more frequently than their untreated counterparts.
For these bands, stability is crucial, providing a foundation for health, decreased parasite load, and reduced offspring mortality. Disrupting this natural order had observable consequences, with band males engaging in more aggressive behaviors and experiencing stress due to increased vigilance.
Human Influence on Natural Processes
Beyond detailing the research findings, Dr. Nunez and I explored broader ethical questions about human intervention in natural processes and the inherent challenge in determining how much intervention is too much, especially considering how contraception attempts to mitigate ecological impact without resorting to more drastic measures, such as roundups or culls. The discourse delved into how human involvement can sometimes exacerbate the very issues we aim to resolve, and it questioned our role and responsibility towards animals.
Contraception Challenges and Future Implications
One of the pivotal aspects of the conversation was how the kind of contraception used, operates by inducing antibodies that prevent fertilization. Despite its non-intrusive intention, long-term use among young mares affected their future reproductive abilities adversely. Dr. Nunez underscored the importance of tailored contraceptive plans that allow for periodic breeding breaks to maintain natural behaviors and physiological health.
Conclusion: Ethical Considerations in Wildlife Management
The discussion with Dr. Nunez highlights a significant point for anthrozoologists and wildlife managers: interventions like contraception serve as a learning tool. It challenges us to consider the ethical ramifications of our choices and the extent to which we should intervene in natural ecosystems.
Show Notes:
Episode 4 of series 13: Sex and Animals Transcript
Being a researcher thoroughly acquainted with the Shackleford Banks horses during her PhD, she was uniquely positioned to investigate the behavioral changes noticed by the National Park Service when they introduced contraceptive management. This intervention aimed to control the horse population to protect the island's endangered plants and animals that were being impacted by overgrazing.
Guest Bio: Dr. Cassandra Nunez is interested in the effects of wildlife management practices on target species’ behavior and physiology, and how these patterns can better inform management and advance basic knowledge of the linkages among animal behavior, physiology, and the surrounding ecology.
As human populations continue to grow, the management of wildlife species is becoming increasingly necessary. As stewards of wild populations, we have a responsibility to manage them with the most effective and ethical means possible.
My research suggests that if we are to achieve this goal, we must better understand the potential individual- and population-level side-effects of our management practices. I incorporate the natural history, behavioral ecology, and the physiology of species to better understand these issues, to more effectively conserve and manage animal populations, and to better understand the basic biology of organisms.
Book Recommendations: An Immense World by Ed Yong and Are We Smart Enough to Know How Smart Animals Are? by Frans de Waal
Related Episodes: 99. Reintroductions and Management with Dr Liz Peterson, Dr. Julie Young, and Dr. Rachel Chock (S10)
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