Spot Spotting: Taking the lead on Sri Lankan leopard learning
Early morning, late September, dense high-tree jungle, Willpattu National Park. We’re here in search of the Sri Lankan leopard, but we’re not especially concerned with seeing any. This search is deeper, probing demographics, movements, habits, habitat, prey and prospects, not to mention sex life, social life, communication and adaptation.
With me in the jeep are three big cat scientists, husband and wife senior scientists Andrew Kittle and Anjali Watson, joined by grad student Gyanada Acharya, operating under the Wilderness and Wildlife Conservation Trust’s ‘Leopard Project,’ along with trusty tracker, Bimal and driver Hemantha. Andrew and Anjali are retrieving camera traps set three weeks earlier along dirt tracks, extracting their accumulated data for later download and analysis. A little later, we move the cameras to spots (sorry) further into the jungle. Rains will be coming soon after the long dry season so Anjali and Andrew are anxious to complete their surveys before dirt roads go gummy.
Using GPS, the scientists maintain a shifting grid in camera placements, facilitating meaningful data analysis. Each trap consists of two cameras aimed across the track, one on each side. When a leopard or any other animal trips invisible beams they emit, the cameras fire so that the subject is captured from two sides in the same instant. Anjali and Andrew can identify individual leopards from the shapes and patterns of their spots. With thousands of photos and recorded times they can determine which animals and how many frequent a given location and they can track ranges of particular cats.
Leopards have been called the perfect predator: expert in ambush, stealthy and patient, then quick in attack and deadly in bite. Having outlasted rival cousins lions and tigers that roamed here prehistorically, she is modern Sri Lanka’s sole land-based apex hunter. Because Lankan leopards have no direct competition, they are possibly more active in daylight hours than leopards elsewhere and less likely to haul heavy kill up trees so as to fend off thieves.
An island the size of today’s Sri Lanka could not support two apex predators, though lions and tigers perhaps shared the landscape when low sea levels allowed land bridge migration with India. As one of eight or so recognized subspecies, the Lankan leopard is the only one to enjoy apex predator status.
As Andrew points out, this possible ‘keystone’ role means that studying leopards here is a simultaneous study of its prey and, by extension, the whole ecosystem. It also means that leopards are key to prevailing ecosystem balances. If leopards decline in number, for example, prey species proliferate and whatever they eat comes under pressure.
At a track junction, we exchange banter with tourists in another jeep, who jokingly blame the scientists for the fact that they, like we, have seen little by way of wildlife all morning.I explain that wildlife does a vanishing act whenever I climb into a safari vehicle. In general, when Anjali and Andrew encounter jeeps reporting leopard sightings, they are likely to head off in the opposite direction: chasing random sightings is too distracting from their main work. As we bounce along between sites, however, we observe leopard tracks in the sandy surface of the so-called road. An adult male has passed here in the past few hours.
Leopards use the roads for ease of movement but also as territorial boundaries, patrolled with scent markings. Adult male prints are squarish, with quirky little features that you can use to distinguish different individuals if you know how to look. Lacking such features, female prints are useless for this purpose.
There are 3.5 adult females for each adult male at Yala national park and the Project seeks to ascertain whether a comparable ratio prevails at Wilpattu. Scientists map three different types of range, overlapping, onto territory. Females occupy territory based on food supply for themselves and their young. Males occupy larger territories based on access to females as well as prey.
Transient leopards, mainly males, defend no particular territory but nevertheless move within mappable ranges. Since male and female cubs get born in roughly equal numbers, males must suffer high attrition to yield the skewed sex ratio among adults. Sources of attrition may include fights with other males, contending with more dangerous prey due to territorial exclusions from the easier stuff, malnutrition and its concomitant health problems, and roaming near human settlements whose inhabitants may kill nuisance animals.
By late morning, Anjali and Andrew are strapping camera traps into their new locations. When we reach the right general area for a trap as informed by GPS, tracker Bimal proves his expertise at quickly finding trees properly aligned on opposite sides of the track for camera placements. Andrew credits him with a sixth sense about picking the right trees, a valuable ‘tracking’ skill unrelated to finding wildlife. With axe and machete, Bimal and Hemantha set about clearing underbrush between the selected trees and the sandy dirt track.
Optimal positioning puts the two cameras far enough from the track to capture the whole animal in photos but close enough to catch the spots clearly. The basic operation for each trap should not take long, but problems invariably pop up. At our first installation site, there is suddenly a traffic jam as six or so safari jeeps squeeze past us and each other. It takes about ten minutes to clear, during which no work can be done. Tourist bungalows sit nearby, which explains the pile up of wildlife enthusiasts.
During the pause, Andrew points out a leopard ‘scrape’ by the edge of the trackway. The animal makes two swipes toward itself through the dirt that come together into a ‘V’ shape. It then daubs scent at the point of the V from anal glands. Anjali describes such scrapes as ‘calling cards.’ They mark territory so as to prevent confrontation among crowd-avoiding leopards and provide intriguing information such as whether a female is in her estrus.
At sites two and three both, one camera is at first strapped on a little too high, so it must be removed both times and re-fastened at the right level. At site three, one of the cameras repeatedly refuses to fire. The scientists tinker for fifteen minutes before solving the problem. At each site, Andrew and Anjali take turns on all fours, crawling leopard-like past the cameras to make sure they are working properly. Anjali thinks Andrew does the better leopard crawl but hers has its own je ne sais quoi. Zoology is fun.
On the morning I need to depart, Andrew and Anjali head into the park with Project staffer Nimalka Sanjeewani for a ‘prey count.’ Leopards are supremely adaptable as carnivores, so plenty of creatures number among their prey from time to time: you cannot meaningfully try to count them all. Hence, the Project executes ‘transects’ of selected prey species along with species of special interest: four kinds of deer (spotted, barking, sambhur and tiny, shy mouse deer), along with porcupine, jackal, boar, land monitor, buffalo, sloth bear, grey langur, toque macaque and elephant. (Leopard beware: many of these critters are dangerous, so try to avoid the grown-ups.)
There are three routes in each transect, each of them requiring a morning to complete, each beginning at exactly the same time in the morning. Transects are performed repeatedly over time so as to yield data that can be analyzed comparatively. Jeeps proceed at painfully slow speed so as to avoid spooking the subjects and to facilitate accurate counts. Scientists record prey numbers, ages, sex, distance from jeep and odometer reading from the start point. Zoology is thrilling.
Scat analysis is a third critical Project activity. Scientists gather poop for close inspection back in the lab. Leopards digest meat and excrete quickly, so prey fur comes through neatly in droppings. Identifying fur and analyzing relative proportions illuminates leopard diet as it varies from animal to animal, place to place and time to time. Scat also yields genetic information used in mapping linkages among populations across the island. Zoology is glamorous.
Leopards live not just in protected areas but in diverse jungle habitats throughout the island, including mountain, tropical rain, river valley and dry evergreen forests. They can flourish in close proximity to humans, putting dogs and cattle at risk from time to time. Despite this flexibility and wide distribution, the Lankan leopard now makes the ‘endangered’ list (likely to go extinct) of the International Union for Conservation of Nature based on data provided by Anjali and Andrew: ‘upgraded’ so to speak from its previous classification as merely ‘vulnerable.’
Always at risk on islands, an apex predator confronts compounded danger from a fast-growing human population like Sri Lanka’s. Heavily hunted for sport in the past and poached for skins, leopards now face mounting pressure from habitat encroachment, forest fragmentation, ongoing poaching and human-leopard conflict killing. The conversion of uncultivated land to paddy fields poses a serious threat.
Having worked at Yala national park for many years, the Leopard Project currently supplements its Willpattu surveys with research in the central highlands. Focus there is on determining distribution and movement in fragmentary mosaics of tea estates, stream valleys and quasi-isolated forest patches, some of them on ridgetops too high and steep for planting.
Gyanada and Nimalka have surveyed tea plantation workers on leopard encounters. With its accumulating knowledge as to demography, ranges and behaviour, the Project paves the way for well-considered and integrated leopard conservation programs. At the moment, for example, it seems possible that local leopard populations are all in touch with neighboring populations through movement pathways, but it also seems possible that some populations have been cut off. Should we emphasize protecting current pathways or developing new ones?
Establishing ‘source and sink’ dynamics could also be a key takeaway. Source and sink inquiry recognizes that some habitats are favourable while others are marginal. High birth rates in favourable habitats sustain a dense population but some animals may regularly get pushed into more marginal habitats where deaths outnumber births. In an island-wide system, could Wilpattu be a source and central highlands a sink? Could there be more localized source/sink dynamics? (By the way, confirming source/sink relations would mean, despite the old saying, that some leopards do in fact change their ‘spots).
Understanding source/sink dynamics could aid in wise design of conservation efforts within limited resources. Should we, for example, stress protection of source habitat by building more water holes or focus instead on enhancing sink habitat by helping tea estates deal with nuisance leopards non-lethally? Lanka’s leopard will not long survive without strong, informed and thoughtful conservation effort. Aside from her own craftiness and resilience, her best hope for now lies with the Leopard Project.
(From Echelon’s archives: published in 18 November, 2015)