A tenth black rhino has died in Kenya after wildlife workers relocated the animals to a new national park, a major setback for a critically endangered species.

The rhino was one of 11 moved to the Tsavo East National Park this month. One rhino who survived the transfer was injured by a lion in an attack at its new home, Tourism Minister Najib Balala told reporters Thursday.

Wildlife officials are monitoring the rhino closely as it undergoes treatment, he said.

An investigation concluded most of the rhinos died after drinking water with a high concentration of salt at their new home. As a result, they suffered from dehydration, upper respiratory tract bacteria and gastric ulcers, Balala said in a statement.

“The high salt levels led to dehydration that triggers thirst mechanism, resulting in excess water intake of the saline water that further exacerbates the problem,” Balala said.

Wildlife officials had conducted water and environment quality assessments at the new park, but the results were not considered before the move, he said.

He blamed the animals’ death on negligence, and poor communication and coordination among the officers involved in the transfer. Several wildlife officials have been suspended over the botched transfer.

Why were the animals moved?

The rhinos were moved from Nairobi and Lake Nakuru national parks to Tsavo East National Park to start a new population in the area.

“At a time when three rhinos are poached on average a day for their horns, any losses are particularly painful,” said Mohamed Awer, CEO of World Wildlife Fund Kenya.

With about 5,000 left worldwide, the black rhino is critically endangered, according to the World Wildlife Fund. By the end of last year, Kenya had about 745 black rhinos, according to Kenya Wildlife Service.

Through relocation and density management, conservationists hope to increase the growth rate and strengthen the population’s gene pool.

Rhino conservation is crucial

Rhinos are targeted by poachers, fueled by the belief in Asia that their horns cure various ailments. Experts say the rhino horn is becoming more lucrative than drugs.

The western black rhino was declared extinct seven years ago as a result of poaching. Just this year, the world’s last male northern white rhino died, leaving the subspecies on the verge of extinction.

All five remaining rhino species worldwide are considered threatened, according to the conservation group Save the Rhino.

Experts say if poaching continues, rhino deaths could surpass births.