What do we know about snow leopard birthing dens?

The man-made rock wall of snow leopard Anu’s den in Mongolia. Photo SLT / Panthera

Snow leopard birthing dens are also called natal dens. They are used by wild females when ready to give birth and are almost impossible to find because of the cat’s elusive nature and the remote, steep mountainous terrain in which they live. But in a world first recently, the Snow Leopard Trust / Panthera Mongolia study found two dens belonging to radio collared female cats.

What do we know about snow leopard dens to date? The answer is not that much. The Mongolia study will provide lots of new information. The two dens found by the research team are both high up in narrow rock canyons and only six kilometres apart.  Interestingly the first one found is a large cave with a manmade rock wall blocking off the front entrance. Presumably local people had made it for shelter or to shelter their domestic livestock. The female snow leopard named Anu by the research team found it and thought it was a good place to give birth to her one cub. Obviously she was not disturbed by smells of the human or animal previous occupants.

The other den was up a canyon in an enclosed narrow rock crevice. The female called Lasya, gave birth to two cubs there.

“As we stood outside the den we could hear the cub and smell the cats but not see anything inside the den, “said PhD student Orjan Johansson. Tom McCarthy, Executive Director of Panthera’s Snow Leopard Program, said “We have spent years trying to determine when and where snow leopards give birth, the size of their litters, and the chances a cub has of surviving into adulthood.”

New cub in a cubbing den with saw dust at Philadelphia Zoo. Photo Philadelphia Zoo.

Cubs remain in their protective dens while the mother snow leopard hunts, and she comes back frequently to nurse and feed them. Female snow leopards rear cubs on their own. They have no male partner or other females to help take care of the young. This means the cubs are alone for some  time, so the den must be in a secretive hard to find place.

What features does the ideal den have? Apart from being remote it should have a narrow entrance easily guarded, and perhaps a flat ledge in front from which the cat can watch for threats and for prey to capture. There should also be a good water source nearby. From the SLT / Panthera photos we see the earthen floor of the cave is covered in dried grass.

The mother will try to hunt close to the den, but depending on where wild prey like argali, ibex and marmots etc are located she may have to go long distances. For her to be confident of leaving cubs the cave must be concealed well.

Perhaps the mother even choses more than one den site before birth so she has a backup one to move the cubs to should she need it. This happens in some cats like cheetah for example when they perceive their first den to be unsafe.

Does the female use the same den for cubs in following seasons? We know snow leopards cover huge amounts of area in their wanderings, sometimes hundreds of square kilometres. However some researchers believe female cats do return and have estimated long use of the same den by a cat by the amount of fur, bones and other litter found there.

To date a lot of researcher’s knowledge of snow leopard behaviour in dens and during birth is based on observations of snow leopards in zoos.

In captivity zoos provide the pregnant snow leopard with a breeding den (also called a cubbing den) often made of wood or concrete and lined with straw or saw dust to keep the floor dry and well drained. In recent years zoos have been able to place a camera into the birthing den so that many videos of births are now available.

Zoo staff have learned that the pregnant female needs quiet and a place where she can feel completely safe. In earlier research it was found loud noise and strange keepers can affect the pregnant female adversely and in some cases cubs were born prematurely and died.

Darla Hillard of the Snow Leopard Conservancy wrote about the world’s first ever radio collared snow leopard and her cubs’ birth in 1985. The research team decided not to investigate the den because of their concerns about the impact on mother and cubs.

“It became clear that our collared female #965 had mated during this time (1984) for the following spring her activity pattern changed so abruptly that we knew for sure she had given birth.

From telemetry, we knew where her den was situated, and the temptation to have a look was almost overwhelming. The uncertainty of what #965 might do if her neighbourhood were invaded by humans ruled out any possibility of exploring the area what if she abandoned her babies, or tried to move them away and one or all of them died? We had no choice but to leave for our summer break without knowing how many cubs had been born to #965, missing the good chance of seeing the offspring of the world’s first radio collared snow leopard. We could only hope to recontact her when we returned in the fall, and that we’d get a glimpse of the cubs.”

Darla writes that later they saw her with two happy and healthy cubs.

We look forward to more information on the mothers and cubs in the SLT / Panthera study over the coming year.