Photograph of Cassandra Nuñez

Dr. Cassandra M V Nuñez

  • Affiliate Faculty


Social Media and Websites

Research Area

Area of Expertise

  • Behavioral Ecology


  • B.A., Laboratory Psychology, Douglass College, Rutgers University, 1993
  • Ph.D., Behavioral Ecology, Princeton University, 2000

I am an Affiliate Faculty member in the NREM Department, no longer at Iowa State; therefore, I am no longer able to accept students who are studying (or would like to study) at ISU.

My research integrates animal behavior and physiology in the wild to answer both applied and basic questions, using feral horses as a model system.  Much of my current research has focused on the unintended side effects of contraception management on the behavior and physiology of feral horses, but I have also studied mother-offspring relationships and the importance of sociality to offspring survival. 

Contraceptive Management: My research has shown that contracepted mares are less loyal to the band stallion; they change social groups more often, particularly during the non-breeding season.  In addition, contracepted mares extend reproductive cycling into the non-breeding season.  How do these changes in behavior and reproductive physiology affect other members of the population?  For example, has there been an increase in the escalation of male-male conflicts in an attempt to retain contracepted mares?  Are levels of stress, measured through fecal cortisol, higher in groups that include more contracepted mares?  Furthermore, how might the use of immunocontraception affect population fitness?  Does stimulation of the immune system to achieve infertility select for individuals with low immunocompetence?  Answers to these questions can help managers make more ethical and responsible decisions regarding the population control of species. 

Mother-Young Relationships: How do differences in mothering strategy contribute to offspring survival?  What can differences in communicative behaviors of mothers and infants tell us about the function of communication for different individuals?  What do we really know about adoption in the wild?  Answers to these questions can help researchers better understand the function of the juvenile stage in mammals and the importance of maternal effort and style to recruitment.

Selected Publications 

(*undergraduate author)

Nuñez, C.M.V. 2018. Consequences of porcine zona pellucida immunocontraception to feral horses. Human–Wildlife Interactions, 12(1):131–142,

Nuñez, C.M.V., J.S. Adelman, H.A. Carr*, C.M. Alvarez*, D.I. Rubenstein. 2017. Lingering effects of contraception management on feral mare (Equus caballus) fertility and social behavior. Conservation Physiology, 5(1): cox018; doi: 10.1093/conphys/cox018.

Nuñez, C.M.V., J.S. Adelman, D.I. Rubenstein. 2015. Sociality increases juvenile survival after a catastrophic event in the feral horse (Equus caballus). Behavioral Ecology, 26(1), 138–147. doi:

Nuñez, C.M.V., J.S. Adelman, J. Smith*, L.R. Gesquiere, and D.I. Rubenstein. 2014. Linking social environment and stress physiology in feral mares (Equus caballus): Group transfers elevate fecal cortisol levels. General and Comparative Endocrinology, 196: 26-33. doi:

Nuñez, C.M.V., J.S. Adelman, and D.I. Rubenstein. 2013. A free-ranging, feral mare (Equus caballus) affords similar maternal care to her genetic and adopted offspring. American Naturalist, 182:674-681.

Nuñez, C.M.V., J.S. Adelman, and D.I. Rubenstein. 2010. Immunocontraception in wild horses (Equus caballus) extends reproductive cycling beyond the normal breeding season. PLOS ONE, 5(10): e13635. doi:

Nuñez, C.M.V., J.S. Adelman, C. Mason, and D.I. Rubenstein. 2009. Immunocontraception decreases group fidelity in a feral horse population during the non-breeding season. Applied Animal Behaviour Science, 117: 74-83.