My research explores changes in the social and sexual behaviour of feral horses that may be correlated with the application of the immunocontraceptive vaccine Porcine Zona Pellucida (PZP).

A potential side effect of PZP treatment is a decline in mare (mature female) fidelity to the harem stallion (mature male). Though leaving the harem is associated with negative fitness costs for the mare, this behaviour has been reported more frequently in populations of PZP-treated horses.

In this photo, young bachelor stallion (an unattached male) Miocene is courting the four year old mare, Niyaha. Niyaha has been with four harems (outside of her birth harem) in her four years of life. Her latest situation is the most unusual as she has found herself among a group of bachelor stallions. Horses are highly motivated for company, and while her current harem is atypical, she remains with the boys and has allowed Miocene to demonstrate particular interest in her.