SANTA MONICA — Five litters of mountain lion kittens have been discovered in the Santa Monica Mountains in what researchers are calling the “Summer of Kittens,” the National Park Service announced on September 2.

The five new litters have brought thirteen mountain lion kittens into the Santa Monica Mountains and Simi Hills. The births are good news for the mountain lion population as earlier this summer researchers stressed low genetic diversity as a problem.

A photo of P-80’s litter. Photo provided by the NPS.

The summer of births started in May when male mountain lion P-63 mated with female P-54, who gave birth to three mountain lions. “It’s always good news to discover a new litter of kittens, but biologists are hopeful for another reason… genetic diversity,” the NPS wrote earlier this year.

At the time, P-63 was believed to be the only collared male in the region, but with the new litters discovered over the summer, the NPS has announced there to be two collared male adult mountain lions.

“This level of reproduction is a great thing to see, especially since half of our mountains burned almost two years ago during the Woolsey Fire,” said Jeff Sikich, a wildlife biologist studying the mountain lion population in the Santa Monica Mountains. “It will be interesting to see how these kittens use the landscape in the coming years and navigate the many challenges, both natural and human-caused, they will face as they grow older and disperse.”

On June 19 researchers found the litter of P-19, a female who has been tracked by biologists for ten years, which consisted of three female kittens. This is P-19’s fifth litter and the father is unknown.

On July 6 P-65’s den and litter were discovered. P-65 gave birth to three kittens, a male, and two females. P-63, the father of the first litter this summer, is believed to be the father of this litter as well.

One of P-67’s litter, photo provided by the NPS

P-67’s den in Simi Hills marked the fourth litter to be born this summer with a male and a female kitten being born. The father, suspected to be P-78, traveled with P-67 for multiple days but left after traveling north to the Santa Susana Mountains, where recently a bobcat and a mountain lion died from ingesting rat poison.

P-80 gave birth to the fifth litter this summer, discovered on August 6, consisting of two female kittens. The father of this litter was again P-63.

For more information on mountain lions and other animals in the Santa Monica Mountains, visit