At home or passing through? What do we know about leopards on Ongava
Leopards are top of the wish list of animals to see on safaris, and Ongava Game Reserve is no exception. While the reserve seems to have perfect terrain for leopards, hills, rocks and tall trees, as well a full suite of their favourite prey, we, and the guests, rarely see them. However, when we check our camera traps, we have quite a few images of them. So what is going on here?
We set out to answer that question using both camera trap images and GPS collars to get a better idea of the number of leopards on Ongava and how they use space on the reserve.
First of all, using spot patterns, we identified a whopping total of 29 individuals from the camera traps images! Yes, 29 leopards, which would result in a density of nearly 10 leopards / 100 km2 on Ongava!! That is a surprisingly large number, so we took a closer look at when leopards were photographed and found an interesting pattern.
While some individuals were seen regularly over the course of the 3 years, some were only seen once or twice, or only in one year and not the following. We concluded that the population was therefore composed partly of resident animals and transients individuals, who did not establish a stable a territory on Ongava and were merely passing through. We identified a total of 10 resident leopards (6 females and 4 males), so our estimated density is 3.3 resident leopards / 100 km2, which is more reasonable and well within the range of known densities across Africa.
Secondly, we used the GPS data to calculate territory size of the 2 individuals. Both had stable territories on Ongava. Like elsewhere, the male had a larger territory (193 km2) than the female (122 km2). Then we used the values of territory overlap published in the literature to estimate how many resident leopards could live on the reserve. We concluded that Ongava could be home to 2-4 males and 3-6 females, which is in agreement with our estimates from the camera trap data.
Male and female leopard home ranges with core of activity shown as red dashed lines. Dark grey areas represent rocky ridges and rugged hills where the leopards spent most of the time. This is one reason why leopards are hard to see at Ongava.
To wrap this up, there are indeed many leopards that could be seen on Ongava, but only a few (~10) actually call the reserve home. An important lesson is that paying close attention to capture histories led to the definition of 2 social statuses (resident vs transient). On top of that, the GPS data helped clarify the status of the female, who was only seen twice on the camera trap images, emphasising the value of combining data from multiple sources. Lastly, the presence of many transient animals in the population raised questions about where these animals come from, where they go after leaving Ongava, and how they interact with resident leopards.
So much work to do on leopards in the future!
You can read the full publication here: NJE