Dead For Years, Ferrets Finally Become Fathers
A two-week-old black-footed ferret is pictured in its nesting box at the National Zoo's Conservation and Research Center in Front Royal, Va. on July 3, 2008. The kit was born on June 21 to a two-year-old mother and a father who had died in 2000. National Zoo reproductive scientists inseminated the female with frozen black-footed ferret semen stored in their genome resource bank -- a frozen repository of sperm and eggs of a variety of endangered species.
Credit: Mehgan Murphy, Smithsonian’s National Zoo

Black-footed ferrets at the Smithsonian's National Zoo have birthed two kits sired by males who died in 1999 and 2000.

These endangered ferrets were artificially inseminated in May with frozen semen from the two dead males, each giving birth to a kit in June, officials at the zoo announced today. 

Three other black-footed ferret kits have been born using this method.

The black-footed ferret is one of the most endangered animals in the world. The ferrets were said in 2006 to be making a comeback, but they continue to struggle.

Once inhabiting the grasslands of the western Great Plains, the black-footed ferret population declined with the loss of the North American prairie ecosystem, the zoo scientists explained. Prairie dogs are the ferret's primary prey, and only 2 percent of the original prairie dog habitat remains today.

A recent outbreak of sylvatic plague (also known as bubonic plague) in a prairie dog population in South Dakota also threatens to decimate ferret populations there.

For more than 10 years, the semen was cryopreserved, or frozen, in the Zoo's Black-Footed Ferret Genome Resource Bank, a repository of frozen semen from the most valuable males. The bank's contents help maintain and even enhance genetic diversity by infusing new genes into the population. A genetically healthy and diverse population has a greater chance of survival in the wild. The sperm samples were collected and frozen in 1997 and 1998.

The bank also serves as insurance against catastrophes in the wild populations, such as a disease outbreak.