Efforts have been made for years to revive black-footed ferrets, a critically endangered species that is native to North America and different than ferrets kept as pets. Now, conservations and scientists have successfully produced offspring--eight kits--using the frozen sperm of a ferret last alive about 20 years ago.

While other black-footed ferrets have been reproduced in captivity from both fresh and frozen sperm, particularly starting in 2008 with more frozen sperm, some of that reproductive material was only 10 years old. Scientists have now managed to reproduce the ferrets from sperm as old as 20 years, which means an opportunity to increase the genetic diversity of the breeding program.

Those scientists, including some at the Lincoln Park Zoo (Chicago), published their research recently in the journal Animal Conservation.

The ferret whose sperm was frozen about 20 years ago was called "Scarface," and was one of the last 18 black-footed ferrets to exist in the wild, doing so in the 1980s, according to a statement.

Others working on this conservation effort include The Smithsonian Conservation Biology Institute (SCBI), U.S. Fish and Wildlife Service, Louisville Zoological Garden, Cheyenne Mountain Zoo, Phoenix Zoo and Toronto Zoo. The current breeding program consists of about 300 animals, said the statement.

"Our findings show how important it is to bank sperm and other biomaterials from rare and endangered animal species over time," said Paul Marinari, senior curator at the Smithsonian Conservation Biology Institute, in the release. "These 'snapshots' of biodiversity could be invaluable to future animal conservation efforts, which is why we must make every effort to collect, store and study these materials now."

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