With only 25-30 Far Eastern leopards left in the wild, it is a rare treat to capture two leopards in one photo (see below). As our automated camera traps use 35mm film, the quality of this photo is far from perfect, but it looks like a mother and her one-year old cub. If so, this is proof that the Far Eastern leopard population is reproducing in our study area. Evidence from our eight-year camera trapping survey in the region, moreover, demonstrates that the leopard population in our study area remains stable.
WCS has been using camera traps since 2003 to monitor Far Eastern leopards in the northern portion of their range along the Russian-Chinese border. Each spring we set-up a series of automated cameras throughout our study area and leave them in place for 8-10 weeks. Each “trap” has a built-in motion sensor that triggers the camera when activated by movement, such as a leopard walking by. As each leopard has a unique spot pattern, we are able to identify individuals and monitor individuals over time. Using this information, we estimate the number of leopards in our study area as well as population trends over time. Over the years, the estimated number of total leopards in our study area has varied from 8 to 14, with an estimated average density of 1.35-1.6 leopards per 100 km2 ,depending on the statistical model used.
Since our first camera-trap surveys in 2003, a total of 36 different leopards have been photographed. During the 2010 survey we photographed 12 different leopards, 4 males, 6 females, one cub and one of unknown sex. Two males have appeared in our photos every year since the start of camera-trapping in 2003, and two females have been seen every year since 2004. This year we took pictures of six new leopards not photographed before, while at the same time one male leopard photographed 2003-2009 was absent this year. The large number of photographs of different leopards over the years suggests high rates of turnover of individuals in our study area, a concerning issue that we are trying to further elucidate through our intensive ecological research project on leopards
in the region.
Of course, it is not just leopards that appear in our photos -- we capture images of all wildlife in the area, including tigers, bears, deer, wild boars, raccoon dogs, badgers, foxes and hares. Since 2003 we have photographed 14 different tigers, and the relationship between the two large cats – tigers and leopards – in our study area is a unique question that we continue to investigate. We usually photograph 3-4 tigers annually, but this year we had a bumper crop of 8 different individuals, 4 males and 4 females, including two tigers never photographed before. These results are not only good for this sub-population of tigers in Russia, but are also highly encouraging for prospects to return the Amur tiger to Northeast China
, which is dependent on tigers dispersing from Russia. Notably, one male tiger, first photographed in 2003, reappeared in our photographs having been absent from 2006-2009 surveys.
Experience gained over the past eight years provide a background for employing camera trapping as part of range-wide surveys for leopards. Traditional snow-track surveys have historically been used to estimate numbers and distribution of leopards because they are logistically easy and relatively cheaper to conduct. However, this approach lacks scientific rigor and is dependent on expert interpretation of tracks – something that few experts agree upon. Camera trapping can be used to assess precision and correct bias in of snow-tracking results, thereby improving overall accuracy of population counts.
A rare sight – two Far Eastern leopards. This photo was taken by an automated camera during WCS’s spring 2010 camera-trap survey. It is difficult to tell from the photo, but this could be a mother (left) with a one-year-old cub (right). If so, this is valuable evidence that Far Eastern leopards are reproducing in our study area.