The death threats against Corey Knowlton have escalated, even as the hunter defends his right to shoot an African black rhinoceros as a way to raise money for conservation.

But some conservation groups have condemned the hunt as sending the wrong signal about saving endangered species.

Dallas-based Knowlton, 35, was identified as the auction winner on social media, and he is currently holed up in a hotel room in Las Vegas, according to media reports.

He contacted the FBI about an onslaught of death threats against him and his family, and he has retained a private security firm for protection.

On that same Facebook page, one person wrote, "You are a BARBARIAN. People like you need to be the innocent