Up to 300 Kaimanawa wild horses may need to be removed from the Waiouru Military Training Area during the muster this April.
Homes will be found for as many of these horses as possible, but any that are not adopted will be destroyed.
The muster is held every two years by the Department of Conservation to manage the herd at a sustainable level of 300 horses within the military area.
This number allowed for horses in the herd to maintain best condition and protected the fragile ecosystems unique to the Moawhango Ecological zone.
DOC operations manager Dave Lumley said rehoming as many horses as possible was an important part of a successful muster.
"Ideally all horses would be adopted, as was the case for the 100 horses mustered in 2016, however, we know it's a real challenge for the groups to find so many suitable homes."
Dedicated not-for-profit group Kaimanawa Heritage Horses has taken on the task of finding new homes for the wild horses.
They will be working hard over the next month taking applications and vetting potential homes.
Muster co-ordinator, Simone Frewin, said Kaimanawa Heritage Horses had applications for only 56 horses to date.
"With only two weeks left until applications close, there's not a lot of time for interested parties to deliberate," she said.
"It's a real concern that some people may simply run out of time, resulting in potentially homed horses being trucked to the abattoir."
Kaimanawa horses were gaining favour among the equestrian community as highly competitive sport horses.
They're the perfect option for those who can't afford to purchase a $25,000 purpose-bred pony but want a chance to be competitive in that class of competition.
"The fact that we're seeing more Kaimanawa horses now rather than just ponies means they're more suited to a wider variety of riders," Ms Frewin said.
"It's devastating to think that many of these horses just won't have a chance."