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.