Kittle and Watson (2007) carried out leopard presence-absence surveys around Sri Lanka intermittently for the past 5 years. The extent of occurrence (EOO) of the leopard in Sri Lanka is estimated at 37,650 km² which is > 50% of the country. However, the area of occupancy (AOO) where reproductive adult leopards have been verified as existing is 11,000 km².
In 2001-02, adult resident leopard density was estimated at 17.9 per 100 km² in Block I of Ruhuna (Yala) National Park (RNP) in Sri Lanka’s southeastern coastal arid zone. This, strikingly, is the same density estimated by Santiapillai et al. (1982) for this area. This 140 km² Block contains what is probably the best leopard habitat in Sri Lanka. It is relatively well protected from poaching and contains sizeable coastal plains and permanent man-made and natural waterholes, which combined allow for a very high density of prey species. Spotted deer (Axis axis) are particularly abundant in this Block, as are water buffalo (Bubalus bubalis) and wild boar (Sus scrofa). Less common, but a seemingly important food source, is the larger sambhar (Cervus unicolor). Two years of prey surveys estimated a prey biomass available to leopards of 7,111 kg/km².
Due to this exceptional prey base and unusual level of management and protection it is likely that the leopard density here is substantially higher than in other parts of the island, protected and unprotected. Kittle and Watson (2007) estimate that the 7,222.8 km² of Protected Areas (National Parks, Strict Nature Reserves, Sanctuaries and Conservation Forests) where leopards are known to reside have a leopard density ½ that of Block 1 Yala. Therefore (8.95 leopards/100 km²) * (7,222.8 km²) = 646.4 leopards. The remainder of the area of occupancy (11,000 km² - (7,222.8 + 140)) = 3,637.2 km² is not protected. We estimate that the population density in these unprotected areas is ½ that of the protected areas = 4.48/100 km². This results in 162.9 leopards residing in non-protected areas.
In total the estimated leopard population in Sri Lanka is (25.1 in RNP, Block I) + (646.4 in Protected Areas) + (162.9 in unprotected areas) = 834.4.
It is apparent from the above method that this is a rough estimate as different habitat types are expected to have varying densities. Kittle and Watson (2007) plan future work in the central highlands (submontane/montane forest) of Sri Lanka which will allow estimation of population density in this region with much greater accuracy. Furthermore, the above estimate does not take into account the Wanni jungles of the far north, which due to the present conflict are inaccessible. It is expected that these jungles, some of the most dense and contiguous in the country, are home to leopards. However, the impact of the conflict is unknown. Due to these factors it is wise to be prudent and assume large confidence intervals, making the estimated range of leopard numbers in Sri Lanka 700 – 950.
No subpopulation is larger than 250, and the population is believed to be declining due to numerous threats including poaching for trade (primarily to India) and human-leopard conflict (Kittle and Watson 2005).