By Dr. Sriyanie Miththapala
The other day, in my continuous and losing battle to keep my bookshelves in order, I found three management plans written for the conservation of elephants in Sri Lanka. I shall not write about their content (which, over three successive decades, was much the same) nor how much of these plans has been implemented (on a scale of 1 to 10, possibly 0). What I shall present in this essay is the point of view that although much attention has been paid to this charismatic species, our focus in Sri Lanka should be directed instead to its top carnivore – the leopard, Panthera pardus.
In an ecosystem, all species that eat the same type of food such as herbivores, which eat plants, belong to a single trophic level. Because some energy is always lost in metabolism and waste products, each trophic level can support a smaller number of animals than the previous trophic level. This results in decreasing groups of numbers that form a pyramid, known as the ecological pyramid of numbers. At the lowest and most numerous level, are the primary producers, plants. At the next level, lower in numbers but higher on the pyramid, are the primary consumers, herbivores. Next come the secondary consumers, carnivores, still fewer in numbers. At the very apex, very scarce in number, are the top carnivores – a single, ‘reigning’ species of predator.
In 1989, the late and great mammalogist John Eisenberg wrote: “The removal of a top carnivore from an ecosystem can have an impact on the relative abundance of herbivore species… In the absence of predators, usually one or two herbivore species come to dominate the community. The consequence is often a direct alteration of herbaceous vegetation near to the base of the food web. Top carnivores have an important role to play in the structuring of communities and ultimately of ecosystems. Thus the preservation of carnivores becomes an important consideration in the discipline of conservation biology.”
Since Eisenberg’s far seeing observation, catch-phrases and terms have been coined to highlight this role of predators. Top carnivores have been called ‘keystone species’ like keystones in ancient buildings (prior to concrete and the advent of lintels), which, because of their position, held up the wall over the door and with it, the entire room. Top carnivores, like keystones, are believed to ‘hold’ or ‘maintain’ the ecosystems in which they exist.
Because they ‘maintain’ the ecosystems of which they are a part, top carnivores function much like umbrellas which provide shade, to afford protection to the ecosystem.
In the 90s, another catch-phrase entered the terminology of conservation biology: ‘top down conservation’ indicating that the processes that maintain ecosystems are exerted from the topmost level of the ecological pyramid to the bottommost level.
I do not believe that it is an issue whether one uses the phrase keystone species or top-down conservation. What is important is that it has been proven that predation, as renowned big cat specialist John Seidensticker says, ‘plays a pivotal role in structuring and preserving biodiversity in terrestrial communities’ and that ‘critically endangered populations of top carnivores are indicators of… declining ecosystem[s].’
Notwithstanding their critical role in ecosystems, historically large carnivores have faced multiple threats from humans. Often, cats such as pumas (Puma concolor) in North America, were viewed for several centuries as serious threats to livestock and considered vermin. Bounties were placed on their heads and they were hunted and extirpated in many areas of the US. Other top carnivores such as tigers in Asia were threatened because they were considered prized game species during the period of the British Raj. This ‘sport’ continued into the 60s and it is reported that from the 1950s to the early 1960s, trophy hunters killed more than 3,000 tigers. Mercifully, these practices were halted and made illegal in the 60s and 70s.
More insidious was an ever-burgeoning human population, which stripped forests to make way for its development; fragmented ecosystems so that once contiguous forests lay in bits and pieces; and then degraded most of what was left. Large, vagile carnivores such as tigers who are known to travel 8 –24 kilometres in search of prey and have home ranges in the far East that extend up to 1000 square kilometres were suddenly ‘cabin’d, cribb’d, confin’d’ in isolated patches which restricted their movements and exposed them to new and menacing dangers: direct conflict with humans and their livestock that led to poisoning, hunting and killing; exposure to new diseases from livestock; death due to road accidents because highways were built between habitat patches; and increased poaching as a consequence of an ever spiralling demand for skins and for body parts that are used in traditional medicine.
Isolated populations were also at risk of homogenisation of their genetic diversity because they were unable to disperse and breed outside their natal areas.
There is no doubt about it – top carnivores are in trouble.
(This is part 1 of a two-part series. The second part of Dr. Sriyanie Miththapala’s essay will be published in The Morning Brunch next week)
Dr. Sriyanie Miththapala’s addendum to the article in 2022:
It is heartening to note that since this essay was written in 2004, many of the questions posed by the author are being answered by the steady and solid work carried out by several researchers, including Andrew Kittle and Anjali Watson, Enoka Kudawidanage, Dinal Samarasinghe, Mr Rukshan Jayawardene and the late Ravi Samarasinghe. Recent researchers include the team from Yala Leopard Diaries, Dushyantha Silva and Team, , Sankha Wittanachchi and Leopocon. Many others such as Gehan de Silva Wijeyeratne, Jehan Kumara, Chitral Jayatilleke, Kithsiri Gunawardena, Luxshmanan Nadaraja, Namal Kamalgoda who, by their spectacular photographs, have put the Sri Lankan leopard on the world map. We are now slowly but surely building a map of the distribution of the Sri Lankan leopard on the island; know that they are found in different habitats, and can survive in tiny fragments of forests; beginning to understand the way these animals use space in these habitats; what they eat; and when they are active. Sadly, we are also seeing, far too often, images of snared leopards, and learning also about increasing threats to these magnificient animals in the face of shrinking habitats.
Advances made so far are excellent. But we still have far to go to build a solid foundation of conservation action to secure the continued existence of the Sri Lankan leopard.
Sri Lanka Leopard Day, which is celebrated annually, was declared based on a proposal put forward by The Wildlife and Nature Preservation Society of Sri Lanka (WNPS), Sri Lanka’s oldest (and the world’s third oldest) nature protection society. The 1st of August a date on which a thesis by Dr. Sriyanie Miththapala confirmed Panthera Pardus Kotiya as an endemic sub species has been declared National Leopard Day in Sri Lanka from 2021.
(The history of wildlife protection in Sri Lanka is almost synonymous with that of the Wildlife and Nature Protection Society of Sri Lanka. At 128 years old, the WNPS is the third oldest non-governmental organisation of its kind in the world and was responsible for the setting up of the Wilpattu and Yala National Parks in Sri Lanka, and the formation of the Department of Wildlife Conservation [DWC])