Denver (AP) State biologists didn't find any new lynx kittens this year.
The Colorado Division of Wildlife has just completed its search for dens with kittens. Biologists have been tracking the number of kittens born since about 2003.
That's when the lynx trapped in Canada and released in Southwestern Colorado since 1999 began reproducing.
Last year, the number of kittens was down from the year before. Biologists say while they're disappointed at finding none this year, it's not unexpected.
Researchers are trying to determine if a fluctuating food source is the reason. The cats' main prey is the snowshoe hare, and fluctuations in the hare's population can drive similar declines among lynx.
Nearly 220 have been released to restore the long-haired cat to Colorado.
A total of 116 lynx kittens are known to have been born in the state, with a high of 50 kittens counted in 2005.
A major milestone was reached last year when a Colorado-born lynx gave birth to two kittens, raising hopes that the population can become self-sustaining.
Lynx are a threatened species whose numbers were decimated by trapping, poisoning and development. The last one was seen in Colorado in 1973 before the restoration program began.