INTRODUCTION: Brumbies are known as the wild horses that inhabit Australia, mainly in the Northern Territory, Queensland and scattered centrally in Western Australia. A few small groups live in Victoria and New South Wales, but none are as large or densely populated. These horses affect the natural habitat in many ways: they reduce vegetation growth, cause soil erosion and impact other animals living in the ecosystem. They are seen as pests in national parks and, in essence, this is the reason for their culling: they cause more damage than they are worth. The only positive thing a brumby herd requires is that they maintain walking and road trails in all state parks. The brumby is a small stocky horse, approximately 14.1 hands tall, and is designed to cope with the harsh Australian environment. Each herd has different characteristics based on its individual location, but overall they are recognizable as the wild horses of Australia. Currently the main source of brumby population control is culling or rehoming through a series of steps. There has been outrage in the media about the cull, particularly aerial shootings, which do not always provide precision in killing horses nor appear to be the most humane option. More options are available to control the ever-growing population, primarily through contraceptive methods that reduce the number of foals each year. Implementing these techniques requires careful planning but can be very effective if used, overall, to reduce herd numbers and allow the ecosystem to return to a somewhat natural state. WHY ARE BRUMBIES A PROBLEM: BRUMBIES are a problem for natural habitats due to their invasive nature... Fo... half of the document... and the administration of GnRH. Although at present the administration of these treatments is not economically sustainable due to the additional time and costs, it has been seen through long-term studies that the use of these vaccines in the regulation of reproductive cycles of mares and stallions can provide a more sustainable and ethical control method that reduces the overall brumbie population and herd size. However, this approach presents many challenges for which solutions have to date been elusive. Ideally, wild horse contraceptive methods should be safe and reversible, effective for several years, practical to administer and reasonably costing while having minimal effect on breeding and/or harem behavior. This ensures that the methods used to control the reproductive cycle are considered humane and ethical.