Feature Article

The Lion’s Den
By Walter Boyce, Director of the UC Davis Wildlife Health Center and ABF Board member

Stars and mosquitoes filled the predawn sky as we prepared to hike to the female lion’s suspected den site. Transmissions from her satellite radio collar led us to believe she just might have a litter of kittens in chaparral south of Cuyamaca Rancho State Park. We had tracked this adult female for two years, and we knew her as a survivor: she lived through the Cedar Fire of 2003, and she recovered from gunshot injuries in 2004.
February 2005 was the first time we thought she might have a litter, so we hiked to the suspected den site with ABF Board member Joan Embery. But that time, we found only a few tufts of hair, an abandoned den, and disappointment. We had been right: she had had a litter. But those kittens had been found and killed the day before, possibly by a male puma who was not the father of the cubs.
Why would a male puma commit infanticide? To ensure that his genes, not another male’s, would live on in the young pumas that would inherit this land.
Now, in July of 2005, our survivor female was again behaving like an attentive mother. Instead of ranging widely from Cuyamaca to Interstate 8, she had returned to the same spot every day for the last four weeks. To the naked eye, the rolling chaparral resembled the sea, giving no hint of the secret lives breathing underneath. But we knew exactly where to look for the lion’s den.
The timing fit. A scheming male would know very well that the female quickly would come back into estrus (heat) soon after he killed her kittens. With a keen nose and a keener sense of purpose, he would track her and her estrus cycle across the landscape. His one-track mind would turn the murderous male into a seducer, ready and waiting to mate when she was ready. And with the puma’s three-month gestation period in mind, we calculated that just enough time had elapsed since the deaths of her last litter for her to have become pregnant and given birth in June.
We set out on our hike as soon as we had enough light to see. Our Wildlife Health Center team was accompanied by Deborah Knapp, manager of ABI, and Chris Pyle, the Emmy Award-winning filmmaker from Wildland Films. Our purpose: to witness, document, and share with others the life and death story of southern California pumas.
As we moved up the Pacific Crest Trail, we checked our radio receiver for signals from the female’s radio collar in order to be sure she had not yet returned to the den site. Most pumas are on the move only from dusk to dawn, either hunting for prey or returning to the site of a previous kill. During the day, they hunker down in their day beds under dense vegetation. We had only a narrow window of time before she would return from her night-time foray, and we didn’t want to meet her at the den.
An hour into our hike, we were relatively close to the suspected den site. Then we had to bushwhack through chaparral, fighting our way through dense, scratchy shrubs taller than our heads. We knew the den should be somewhere within a radius of 50 meters, so we expected to find the kittens with relative ease. We were mistaken.
For the next hour we prowled under and around every pile of rocks or mass of shrubs that might hide a litter of kittens. We found that crawling on our hands and knees was often easier than trying to walk through the nearly impenetrable chaparral. Thunderstorms and torrential rains had pounded the area two days earlier, and now the rising sun forced moisture-charged plants and dirt to surrender a delicious, pungent fragrance that was almost overwhelming.
We all searched expectantly. But looking and seeing are two different things. Eric York, the lead lion biologist, has years of experience reading signs in nature that others can’t see. So it was Eric who noticed the dents in the soil and slightly deflected branches that led us to a puma den site. With his help, all of us saw - or believed we saw - adult puma tracks and a disturbed but empty patch of dirt where kittens had been.
Judging by the fresh signs of activity since the rains had washed the landscape clean two days ago, the kittens must have been there recently. The earth at the site even smelled like animals. Energized, we redoubled our search efforts, sure that the cubs must be nearby. But even after another hour, we still had no sign of kittens.
Hot, discouraged, and just about ready to give up, we had separated as each of us followed our own hunches about where to look. So I was alone when I heard a rustle in the brush near me. I called out to see who was there. The answer was a growl so deep, I felt it in the pit of my stomach.
Suddenly super-alert, I hustled back to where I had left the receiver that picks up signals from the pumas’ radio collars. Dialing in the right frequency, I heard the loud clear beeps that told me what I already knew: Mom was back. And she could have only one reason for coming so close to me. Her kittens must be nearby. Just then, wildlife veterinarian Winston Vickers called out in an uncharacteristically high-pitched voice cracking with emotion, “Here they are!”
Huddled together under a heap of twigs we had passed several times before, we found four five-week-old kittens. This den site, like the first one Eric found, did not fit any storybook concept of what a den should look like. There were several nice rocky crevices and caves only a few feet away that we had searched and re-searched. But these four kittens were simply huddled together under a few sticks, lying on top of the ground, exposed to the elements.
We had to choose: stay or leave. Females with cubs can be aggressive, but at about 100 meters away, this female was keeping her distance. So we decided to stay.
During our search, the kittens had been silent. Helpless commotion gets results for human infants, but noisy cubs would soon attract unwelcome visitors looking for an easy meal. Now as we reached into the huddle of spots and fur, the cubs began to growl, snarl, and swat at our fingers with their paws. Blue-eyed, unsteady on their feet, and weighing all of four pounds each, they displayed a tiny ferocity that brought smiles rather than fear.
Young kittens are some of the most appealing creatures on earth. If the sight, sound, and touch of a five-week old cub can’t give you a warm fuzzy feeling, then I don’t know what will. The urge to pet the cubs was nearly irresistible. But wild animals are not pets. Stroking the fur of a cat or dog may be soothing to owner and pet. But a puma cub may perceive such intimate human contact as the killing touch of a predator. And its mother may turn executioner if she abandons a litter because it smells like humans.
We gave each kitten (three boys and a girl) a thorough health exam, took a blood sample for disease testing and genetic analysis, and put a small tag on each one so we could identify him or her at a later date. We worked quickly, leaving by midmorning so cubs and mother could reunite.
Our goal now is to follow the lives and movements of these cubs in the years ahead. Will they survive until they leave their mother around 18 months of age? What routes will they take when they leave, and will they find a place to live? Their transition from kittens to sub-adults no longer dependent on their mother will be fraught with hazards. Young pumas will travel dozens of miles in search of a new home range. They may go in any direction, and a puma heading west in San Diego County can soon run into more people than he or she can handle.
As a scientist, I usually try not to project human emotions on wild animals. But finding these vulnerable kittens in the wild was an emotional and uplifting experience. Here in our hands was proof that wild animals still have room to thrive in southern California. I wish everyone could experience the intimate connection that we felt that day with those cubs. I feel privileged to work with these animals, and I feel a responsibility to make sure pumas and other wildlife continue to have safe, healthy, natural habitats.