WA is facing a worldwide backlash from horse lovers after the Aboriginal Lands Trust began a mass cull of thousands of feral animals on two of its stations in the Kimberley.
The ALT ordered the shooting to start this week because of concerns about the welfare of the horses and the environment on the Lake Gregory and Billiluna leases.
An aerial census by the Kimberley Rangeland Biosecurity Group late last month found there were almost 6000 feral horses on the leases.
Aboriginal Affairs Minister Peter Collier said the horses were found to be drinking salt water, dead horses were discovered stuck in deep mud, Aboriginal homes had been damaged and pasture for cattle had been decimated.
"The WA Government, as part of its due diligence, ensured the ALT investigated all other viable options of dealing with the situation and are confident that an aerial cull is the only viable and humane method to follow," he said.
"The RSPCA was involved in the investigation and agrees with the ALT that an aerial cull is the most humane option open to them to deal with what is a difficult situation."
Kimberley Wild Horses co-ordinator Libby Lovegrove said the cull had started in virtual secrecy after years of fighting to save the horses.
Ms Lovegrove said she had alerted horse rescue groups around the world as soon as she became aware that the shooting had started. "We are devastated," she said. "It is a ridiculous decision to destroy these beautiful horses which pose no threat to the environment."
ALT chairman Clinton Wolf said attempts to deal with the problem had been held up by various State Government departments and ministers.
Hundred of horses suffered horrific deaths after they were stranded in mud at Balgo last year.