National Park Service researchers discovered two litters of mountain lion kittens in the Eastern Santa Susana Mountains in California.
The kittens were ear tagged and returned to their respective dens earlier this month.
Two female kittens were tagged on June 8 and are known as P-48 and P-49. NPS has been tracking their mother, P-35, a 6-year-old female, since April 2014. Based on remote camera images, biologists are suspecting that P-35's previous kitten, P-44, did not survive into adulthood.
The second litter was born from P-39, an approximately 5-year-old female. NPS has been tracking her since April 2015. She gave birth to a male known as P-50, a female known as P-51 and another male known as P-52. On June 22, researchers found the litter living in a cave-like den hidden beneath large boulders.
Based on GPS location, the father of both litters is suspected to be P-38. He was found traveling and spending multiple days with P-35 and P-39 months before the kittens were born. NPS has collected samples from the kittens for genetic testing to determine paternity.
NPS was able to locate the dens by analyzing the GPS locations transmitted from the mother's collar. However, it can prove to be difficult to find exact locations because mothers choose to hide their kittens in thick brush and hidden crevices for protection.
"Despite the challenges that mountain lions in this area face, the animals we've studied appear to be reproducing successfully ... the real challenge comes as these kittens grow older and disperse, especially the males, and have to deal with threats from other mountain lions and also road mortality and the possibility of poisoning from anticoagulant rodenticide," Jeff Sikich, a biologist with Santa Monica Mountains National Recreation Area, said.
These are the 10th and 11th litters of kittens marked by NPS at a den site. Previously, two additional litters of kittens were found when the kittens were already 6 months old.
2 litters of mountain lion kittens born in California mountains