On a cold spring morning in 2014, I started walking from the high-altitude village of Kibber in the Spiti Valley of Himachal Pradesh, towards a pasture near Chichim village, six kilometres away. I was surveying the wild herbivores of this region with the help of Lobzang, a naturalist from Kibber.
These rugged, high mountains are the ideal habitat for wolves, the snow leopard, the wild cat with the longest and fluffiest tail, and its enigmatic prey: bharal and Asiatic ibex.
Lobzang and I were walking quickly down the slopes, past agricultural fields still covered in frost, when we noticed a sudden movement near a snow-covered culvert. Instantly on high-alert, we stopped in our tracks. Nothing happened. All we could hear was the freezing wind sweeping across the plateau and the reverberating calls of the yellow-billed choughs.
Then, just when we were about to carry on, an angular head emerged from a pile of boulders. It was greyish-black in colour, with a pointed face, dark, bright eyes, and ears that were widely spaced and rounded. A stone marten. It was almost impossible to distinguish the animal’s head from the surrounding rocks — it was so well camouflaged, and aptly named too. The marten remained motionless for about half a minute. Then, within the blink of an eye, it left the culvert, scuttled across the trail, and disappeared behind another boulder. So fast was it that its signature white throat-patch and twin projections towards the forelimbs, seemed like a flash of light.
The stone marten, aka Martes foina, is a small carnivore species from the Mustelidae family. It weighs between 1.1 and 2.3 kilos, and is familial cousins with the pine marten, yellow-throated marten, and the Nilgiri marten. The stone marten is found across much of Europe, and central, south and Southeast Asia, from sea level to altitudes of 4,000 metres. In India, they have been observed at heights of up to 4,200 m along the Himalayas and Trans-Himalayas.
Stone martens are largely crepuscular and nocturnal, meaning they are most active during twilight hours and after dark. They are not known to dig burrows, but inhabit natural rock fissures, and feed on a variety of food. Their diet may vary seasonally and regionally, and is mainly composed of small mammals like Royle’s pika, lagomorphs like the Himalayan woolly hare, and some vegetation. During winter and spring, stone martens eat less vegetation, and consume invertebrates as well.
Stone martens normally mate during the months of June and July and females give birth to offspring in March-April, a gestation period of over seven months. The usual litter size varies from three to seven individuals.
The only published home-range estimate of stone martens is from a study conducted in northeastern Spain, which reports an area of half a square kilometre. To better understand the species, researchers from India’s Nature Conservation Foundation and Snow Leopard Trust conducted a study of the stone marten in Spiti using images from camera traps. The data was then used to assess the animal’s activity pattern in relation to prey species, and native and introduced predators, the red fox and feral dogs, respectively.
The study revealed that the stone martens of Spiti are almost completely nocturnal and that their activity overlaps temporally (time-wise) with that of the hare, and spatially with that of the pika. This allows martens to access both species. Similarly, the study showed that stone martens and red foxes had high temporal and spatial overlaps, indicating that martens may not be facing predation from foxes, else they would avoid them. On the other hand, feral or free-ranging dogs and martens showed hardly any overlap of space and time, indicating avoidance behaviour. Overall, activity of the stone marten seems to be a balance between consuming hares and pikas, while avoiding larger predators like dogs.
Small carnivores like the stone marten play an important role in their ecosystem. By preying on pikas, hares, and rodents, they keep the population of herbivores in check, which in turn regulates the flora of their alpine and subalpine grassland habitat. And these grasslands are invaluable, providing food for larger wild herbivores, domesticated livestock, and medicinal plants and wood fuel for the many local communities.
And yet, the stone marten and other small carnivores of the Himalayan and Trans-Himalayan region are a relatively unexplored bunch. They are small but fascinating animals, awaiting attention from ecologists and conservationists.