Saturday, January 14, 2017

Leopards in the forest - new Chimp&See mini-project on predators

In December, we started another mini-project on Chimp&See preparing to assess predator density at the research sites. What sounds a little dry and analytical is actually quite exciting: with the help of our volunteers, we will identify individual leopards to get a clear picture of how many of them live in an area. These big and beautiful cats are known to prey on smaller primates and ungulates, but do not necessarily stop for bigger species, like chimpanzees.

Leopards in the forest – a short introduction 
We have already seen leopards on our camera traps at several sites in West and Central Africa. Leopards are the largest forest predators; at the savannah site Dry Lake we’ve seen leopards and lions alike. Much knowledge about leopards comes from the better known open habitats in East and South Africa, whereas forest leopards need to be studied better in their unique environment. Here, leopards do not have any other competition by big cats (no lions or cheetahs in the forest). The only other major predators are eagles - that are more relevant to more arboreal species - and the chimpanzees themselves.

Forest leopards live in the dense and moist rainforest with limited visibility of potential prey. As rainforests do not have a markedly seasonal rhythm like savannahs, there are also no significant prey migrations, offering a constant, but smaller supply of potential food for these carnivores. As a consequence, their home ranges are thought to be bigger than in open savannahs and woodlands, and the density (the number of individuals per square kilometer) to be higher. Although leopards are territorial and solitary, we expect a considerably overlap of their territories.

Leopards are opportunistic hunters. In addition to ungulates and smaller mammals, leopards hunt monkeys, but also chimpanzees and bonobos. Usually, they hunt prey smaller or equal in body size than themselves, but are known to successfully attack prey animals much bigger, like the large-bodied Jentink’s duikers. They prefer more terrestrial primate species that live in big groups, like sooty mangabeys. Forest leopards hunt mainly during the day and on the ground with an activity peak at dawn and dusk. This daytime hunting follows the diurnal activity pattern of their main prey species. Savannah leopards on the other hand, and also leopards in closer proximity to human settlements, prefer hunting at night – also because other competitors (e.g., lions) might prefer daylight hunting or steal the prey.

Leopard matching at Chimp&See 

To assess the predation risk of chimpanzees and other primates, we therefore need to know how many leopards live at one site. The mini-project will attempt this goal in two steps: first, we will tag all leopard videos with the respective age classes and, if possible, sex of the individuals as well all visible body sides to prepare for a direct comparison of the fur pattern. In a second – but eventually parallel – step, we compare this pattern and other traits of the leopards to assign individual IDs. The leopard fur pattern of dark spots and rosettes is highly individual and allow confident identification of an individual – at least if we get the same body side on camera twice. A detailed tutorial helps the volunteers to discuss their findings and present their arguments on the discussion board.

A detailed tutorial explains how to compare the fur patterns of leopards and present findings
Once a leopard is identified as the same individual in two separate video sequences, the volunteers can name it. Everybody can try it. Like all cats, leopards are extremely beautiful, elegant, and powerful animals. Even if you do not find a match, a close look on our footage is worth all your time.

  • Jenny D. Spatial organization of leopards Panthera pardus in Taï National Park, Ivory Coast: is rainforest habitat a ‘tropical haven’? Journal of Zoology, November 1996. DOI: 10.1111/j.1469-7998.1996.tb05296.x 
  • Zuberbühler K, Jenny D. Leopard predation and primate evolution. J Hum Evol. 2002 Dec;43(6):873-86. 
  • Boesch C. The effects of leopard predation on grouping patterns in forest chimpanzees. Behaviour 117 (3-4) 1991
  • Bailey T. N. 1993. The African Leopard: Ecology and Behavior of a Solitary Felid. Columbia University Press, New York, 429 pp.

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