Story highlights Two species of antechinus are on an endangered species list

These marsupials mate so furiously that the males stress out and die

(CNN) They are small, mice-like critters known for their marathon mating sessions, which can last up to 14 hours. And that may be their undoing.

The Australian government has added two species of antechinus, the black-tailed dusky and the silver-headed, to its endangered species list, saying all that sex is killing them.

During mating season, which lasts for several weeks each year, males and females move frantically from one mate to another. There's no courtship, just sex -- with as many partners as possible.

"They literally become a marsupial zombie in their pursuit," Jeff Corwin, wildlife expert and TV host, told CNN.

Males only live about a year, and the females live up to three years, but on average, they both die after a litter is born.

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