The May 2022 Kaimanawa Wild Horse Muster marked the start of a new era in the management of the Kaimanawa wild horse population following the introduction of immuno-contraception as a method of controlling population growth into the future.

After being researched thoroughly over the last decade, technological advancements in immuno-contraception drug efficiencies and successful overseas trials, Kaimanawa Heritage Horses Welfare Society, have been the driving force towards seeing this option implemented in the wild Kaimanawa herd as a complementary option to rehoming.

With musters being held annually or biannually for two decades the need to see an alternative option to help reduce rehoming requirements has long been required and the introduction of a controlled immuno-contraception strategy alongside rehoming will start to bring that change.

One of the founding aims of the Kaimanawa Heritage Horses Welfare Trust was to preserve a wild horse population with minimal intervention. However, the population growth rate of Kaimanawa Horses has meant that re-homing musters have become an annual event. This creates an enormous workload for the volunteers of Kaimanawa Heritage Horses, Department of Convservation (DOC) staff and the NZ Defence Force. Essentially up till now, horses have been allowed to breed only to be mustered and re-homed. This has always been an unsustainable method of herd management.

Since 2009 much effort has gone into looking at more sustainable and long term options to slow the rate of population growth, and eventually reduce the number of horses requiring re-homing, in addition to reducing the frequency of the musters.

Finally, in 2021, Kaimanawa Heritage Horses was able to present a strong enough case to fellow members of the Kaimanawa Wild Horse Advisory Group to see an agreement reached on the use of the immuno-contraception drug GonaCon Equine. Following the approval of the Animal Ethics Committee and installation of the necessary equipment, the first group of around 60 mares received their vaccination at the May 2022 re-homing and subsequent vaccination muster.

One of the most heart-breaking aspects of any re-homing muster is seeing family bands being broken apart to be re-homed. But finally, this year for the first time around 150 horses, comprising vaccinated mares, foals and stallions were released from the muster yards to re-form their bands and return to their home territories back in the ranges. All present agreed it was a magnificent sight and KHH Immuno-contraception Representative, Suzanne Millard, says “From my own perspective it made my 25-year involvement with Kaimanawa horses and the 13-year commitment to promoting contraception as a viable management tool worthwhile.”

Going forward rehoming musters will still be required while contraception is applied to a greater number of mares and the effects of the immuno-contraception programme become known. Monitoring of the wild herd will remain in place through aerial surveys, extensive photography programmes and ongoing data collection to ensure the correct approach can be applied in the future.

To see the addition of contraception as a combined tool toward maintaining a healthy and sustainable wild herd was an exciting achievement and the committed partnerships between KHH, DOC and the Kaimanawa Wild Horse Advisory Group will remain focused on seeing it applied throughout future years.

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