Denver ? The discovery of 10 lynx kittens this spring marks the first newborns documented in Colorado since 2006, heartening biologists overseeing restoration of the mountain feline.

The tuft-eared cats with big, padded feet were native to Colorado, but were wiped out by the early 1970s by logging, trapping, poisoning and development. They are listed as threatened on the endangered species list.

Biologists found no kittens the past two years, possibly partly because of a drop in the number of snowshoe hares, the cats’ main food source.

This year, seven male and three female kittens were found in five dens.

More than 200 lynx from Alaska and Canada have been released in Colorado since 1999. Biologists don’t know how many lynx are currently in the state.