CAT NEWS. NO:41, Autumn 2004
A. M Kittle*^ & A. Watson*
*The Leopard Project, The Wilderness & Wildlife Conservation Trust, Sri Lanka.
Department of Zoology University of Guelph, ON, N1G 2W1, Canada.
The leopard (Panthera pardus kotiya) is the largest of four wild cat species recorded in Sri Lanka where it is the island’s only big cat and its top predator. This population has evolved geographically separated from the mainland species Panthera pardus fusca and is now recognized as one of the nine subspecies of Panthera pardus currently extant in the world (Miththapala et al 1996; Uphyrkina et al 2001). This isolation and subsequent sub speciation further heightens the endangered status of this island leopard.
The leopard has historically been found in all habitats throughout the island (Phillips 1935). These habitat types can be broadly categorized into the arid zone (<1000 mm rainfall), the dry zone (1000-2000 mm) and the wet zone (>2000 mm). The former two zones are characterized by broad lowland swaths while the wet zone is further subdivided into lowland, sub-montane and montane sections. Intermediate zones are also present and usually form gradations of habitat type. The northeast monsoon which occurs from mid-October to January and the southwest monsoon from May to July directly influence the island’s ecosystems.
It has been suggested (Santiapillai 1982) that most remaining populations of leopard are extant only within the country’s remaining National Parks which cover 12% of the country’s landmass. At present approximately 20% of the island remains forested and while relatively large tracts of unprotected wilderness and semi wild land utilized by wildlife remain, this cover is highly fragmented.
Results from our ongoing research in selected habitats as well as an island wide distribution survey indicate that resident populations are still extant in all zones throughout the country. The exception being the more developed and high human populated areas of the western province. While it is expected that populations exist in the far north, where a significant expanse of dry zone forest remains, this area has not been investigated due to the ongoing civil conflict.
Site specific studies
Results from a pilot study (Kittle and Watson in prep) conducted from 2000 to 2002 on a leopard population in Block I of Ruhuna (Yala) National Park in the arid southeast of Sri Lanka, show a density greater than that exhibited in most African studies (Schaller 1972; Hamilton 1976; Bothma & Le Riche 1984; Norton & Henley 1987) This density was comparable to Baily's (1993) in-depth, radio telemetry study in an area of Kruger National Park, South Africa considered to be prime leopard habitat. The minimum home range sizes that we determined in the Ruhuna (Yala) study were similar to those determined for radio-collared leopards in Thailand (Rabinowitz 1989; Grassman 1999) and Kruger (Baily, 1993) but smaller than the majority of studied populations (Schaller 1972; ; Hamilton 1976; Bothma & Le Riche 1984; Norton & Henley 1987; Kostyria A.V. 2004 (unpublished data)).
Our 127 km2 study site within Block I is a protected, managed habitat with permanently maintained water sources. The availability of water throughout the year has allowed for a high density of prey species including Axis deer ( Axis axis ), Sambhar ( Cervus unicolor ), buffalo ( Bubalus bubalis ) and wild boar ( Sus scrofa ). Together with a terrain abundant in rocky outcrops for denning and a lack of interspecies competition, we conjecture that this high prey density allows for a high leopard density.
A study conducted in the 1960's in a similar managed arid zone environment in another of the country's National Parks (Eisenberg and Lockhard, 1972; Muckinhurn and Eisenberg 1971) also indicated a similar population structure to our pilot study although these were crude estimates based on a few home range sizes.
A second study (Oct 2003- March 2004) utilizing camera traps and signs conducted by us in the Hantane region bordering the Municipality of Kandy (pop.100 000+) in the Dunumadalawa watershed forest (1500-1700 m asl) showed a small resident leopard population. The 5 km2 study site was inhabited by 1 resident female and her cub (6 month-1 year old during the study period). They appeared to spend the majority of their time within the study site. A resident male included the study site as part of his larger home range and infrequent evidence of a second adult female and sub adult male were also noted.
The fact that such a small forest area on the edge of a densely populated urban centre is home to resident leopards leads us to believe that this is only part of a larger population. This is supported by the fact that between 2002 and 2004 a minimum of three (3) leopards were poached in this area. Results also showed that individuals were utilizing pinus plantations and the upper fringes of tea estates to travel between fragmented patches of forest. Sus scrofa , Muntiacus muntjak (barking deer) and Hystrix indica (porcupine) were seen to be the most common prey species.
Preliminary investigations into the connections between forest patches and the land use attributes of the area are already underway in order to determine the spatial distribution of leopards in these little investigated, mid-elevation zones.
National Parks and connector forests
Most of the National Parks of the country are within the dry/arid zone (11 of 14) and are all managed landscapes. These Parks form the largest conglomeration of protected forest in the country, characterized by evergreen monsoon forest in the dry zone and scrub forest in the arid zone. Water is maintained to varying degrees throughout the year in created and/or deepened water holes. As exemplified in our Yala study this water availability allows for higher year-round densities of prey and therefore possibly higher numbers of leopard than would otherwise survive in these habitats.
The montane zone currently has only one declared National Park (Horton Plans) and four other protected areas of lesser status (Peak Wilderness Sanctuary, Hakgala Strict Natural Reserve, Pedro forest reserve and the Knuckles range (currently undergoing status change)). Although some small forest reserves do exist interspersed through out the zone these areas have not been considered wildlife refuges let alone leopard habitat. Large tracts of wilderness in the sub-montane and montane zones were cleared and cultivated into coffee and tea plantations in the late 1800’s under British rule. This greatly reduced the extent of forest cover, however higher montane forests (>1900 m) still exist today and are used by leopards in these areas. The study of leopard populations within this zone as well as the extent and direction of dispersal of individual leopards is vital information needed for the long term conservation of this species.
The wet zone, exemplified by the 11 187 km2 Sinharaja rain forest – a UNESCO World Heritage Site - and the only protected area of size in this zone, has a resident leopard population. Areas to the north-west and south-west of this protected forest, including Heycock Mountain, are also turning up evidence of resident populations (Wimalasuriya.S. 2004 pers.comm).
Distribution surveys and studies