NAIROBI, Kenya — A white female giraffe and her 7-month-old calf, whose rare pigmentation mesmerized wildlife enthusiasts around the world, have been killed by poachers in Kenya, officials said, illustrating the challenges of conservation and the persistent and devastating impact of poaching.

The deaths of the giraffes left just one of the unusually colored animals in the country’s wild, a bull, out of a family of three, conservancy officials said.

Mohammed Ahmednoor, the manager of the Ishaqbini Hirola Community Conservancy in northeastern Kenya, where the giraffes lived, said that rangers had confirmed their deaths and that there were photographs of the skeletal remains.

“This is a very sad day for the community of Ijara and Kenya as a whole,” Mr. Ahmednoor said. “We are the only community in the world who are custodians of the white giraffe.”