Old and sick, the world's last male northern white rhino has surprised his keepers by getting up and walking around at a wildlife area in Kenya.

The 45-year-old rhino named Sudan moved during the night and took a "delicious mud bath" after long-awaited rains fell, the Ol Pejeta Conservancy said Saturday on Twitter. It noted that March 3 is U.N. World Wildlife Day and that it had received many messages of concern for the ailing Sudan, who could be euthanized if he continues to suffer from a deep infection on his back right leg.

"He is now resting again and will be attended by the vet team and his keepers throughout the day," said the conservancy, which is also home to the last two female northern white rhinos - Sudan's daughter and granddaughter.

While the rhino subspecies is on the verge of extinction because of poaching, scientists hope to use southern white rhinos as surrogates to carry northern white rhino embryos and give birth. The in vitro process would be conducted using sperm from dead rhinos that is stored in Berlin and eggs extracted by surgery from the females at Ol Pejeta, according to the conservancy.

Some conservationists believe the scientific project stands little chance of rebuilding a viable population of northern white rhinos and say funding and resources should be directed to saving imperiled species with a much better chance of recovery. They refer to Asiatarget="_blank"'>