Tigers have stripes, leopards have spots, right? Wrong. Oddly, leopards in Peninsular Malaysia are jet black in colour, leading many to assume that the country does not have leopards, but panthers.
The fact is, there are leopards here; it’s just that their distinctive “leopard print” is harder to see under their black coat. However, under certain lighting conditions, the spots show up.
Black coloration or melanism is found in some mammal species, especially big cats, and is caused by the agouti gene which regulates the distribution of black pigment within the hair shaft.
But scientists have no idea why the condition predominates in Malaysian leopards. Melanistic leopards are found in Java and southern Thailand as well but both places also have the spotted leopards.
In Peninsular Malaysia, the leopard’s all-black colouration prevents researchers from telling individuals apart when photographed by camera traps. This hinders population estimates. But researchers from Rimba, a group of biologists researching on threatened species and ecosystems in Malaysia, have found a way to solve the problem – by manipulating the mechanism of camera traps.
“During the day when no flash is used, the different leopard individuals are indistinguishable,” says Dr Gopalasamy Reuben Clements, associate professor at Universiti Malaysia Terengganu. “However, at night, the characteristic spotted pattern of leopards can be seen on their coat. All we did was place a piece of sticky tack over the light sensor of the camera. This fools the camera into thinking it’s night even during the day, so it always flashes.”
With the infrared flash firing, the seemingly black leopards suddenly showed complex patterns of spotting, enabling the scientists to discern between different animals, and to gauge their numbers.
They used the method in the Kenyir Wildlife Corridor in north-eastern Terengganu, a forest reserve near Kenyir Lake and Taman Negara National Park. From the camera trap images, they concluded that the area has three leopards per 100 sqkm. The findings were recently published in the Journal of Wildlife Management.
“We could accurately identify 94% of the animals, which enabled us to get an estimate of the population size. We can now monitor this population each year to get a sense of whether leopards in the region are increasing in numbers, or whether they are in decline,” says lead author Laurie Hedges of University of Nottingham Malaysia Campus.
The researchers want to use their new method to study leopards elsewhere in Peninsular Malaysia for, as with tigers, leopards are being poached. Carcasses of leopards with injuries inflicted by snares have been discovered. Also, leopard skins and body parts are showing up in wildlife trading markets in places such as on the Myanmar-China border. Suitable habitats for the leopards are shrinking as forests are cut down for timber and replaced with plantations.
“Some places where I have camera-trapped relatively abundant levels of prey and forest cover, alarmingly, turned up little or no evidence of leopards,” says Dr Ahimsa Campos-Arceiz, an associate professor based at the University of Nottingham Malaysia Campus.
The researchers believe their novel technique will also benefit researchers in Thailand and Java, where melanistic leopards can also be found.
Note: A black panther is the melanistic colour variant of any Panthera species. Black panthers in Asia and Africa are leopards (Panthera pardus) and black panthers in the Americas are black jaguars (Panthera onca).