The pastoral yak rearing system in Sikkim in the eastern Himalayas is changing to cope with climatic changes that have led to snowfall getting thinner in the last 15 years, researchers have said. In an exploratory study, researchers said integration of indigenous knowledge on yak husbandry into policy and scientific decision-making may shield the yak herders and yaks, Bos grunniens, from forthcoming climatic changes.

From the trekking and tour companies named after it to the string cheese and tee-shirts, the yak, a cultural icon, is ubiquitous as one trundles through Sikkim in India, grocery shops in Bhutan, or even the ‘hippie quarters’ of Thamel in Kathmandu, Nepal. The yak provides milk, meat, transportation, dung for fuel, and hides for housing, which are essential for nomadic pastoralists in high altitudes. The warmth and comfort of yak wool, which shelters Himalayan nomads from the frosty winters, has inspired outdoor apparel brands abroad. Yak milk chewies for puppies are another spin-off.

But the “ship of the highland” is now at risk of losing steam to climate change in the Himalayas in addition to other challenges.

Lachen and Lachung

Yak herders of Lachen and Lachung in North Sikkim and scientists working on yaks spoke of changes in seasonal migration patterns, impacting the animals’ milk productivity and reproduction. This, in turn, they said, is leading to drudgery, disease infestation, and mortality of yaks.

The yak cannot tolerate temperatures above 15 degree Celsius. Researchers said the seasonal movement of livestock between fixed summer and winter pastures in land-locked Sikkim enables the yaks to adjust and adapt to the seasonal changes and optimise the use of seasonal pastures at different altitudes.

In Lachen and Lachung, the Dzumsa – the local body that governs the indigenous communities, Lachenpas and Lachungpas – decides the migration track and time in order to conserve pastures at high altitudes through a rotation policy. The Dzumsa fixes the date of movement for all herders, according to the Tibetan lunar calendar and manages the rangeland resources by rotational grazing practices.

Lachung, at 2,600 metres above sea level, means “small-mountain” and Lachen, with an altitude of 2,700 metres above sea level, means “big-mountain” in Tibetan. The two realms in Sikkim’s North District are roughly 60 km apart from each other. Connected by mountain passes that link Sikkim with Tibet, the two areas along the Indo-China border are home to little over 3,000 indigenous inhabitants.

In North Sikkim’s Lachung and Lachen, the local body decides the migration track of yaks so as to conserve pastures through a rotation policy. Credit: Indrajit Das/Wikimedia Commons.

Reduced snow cover

The study records that the majority of the households in Lachen and Lachung owned yaks and about 68 percent of them reared yak for commercial purposes. On average, a respondent herder had 30–40 yaks. Their seasonal migration sees the herders and the animals traverse an elevation of 2,000 metres to 5,000 metres.

“Yak herders recalled that 15 to 20 years ago, lower altitudes [that] used to get snowfall during winter now hardly receive any snowfall. The herders reported...the degradation of pasture, which they felt was due to increased temperature and reduced snowfall,” Feroze and co-authors explained in the study.

Global warming has hit them hard in areas in Lachung, affirms Thupden Lachungpa, secretary of the land committee of Lachung Dzumsa, who was not associated with the study. “The yaks were supposed to be at an altitude of 2,133 metres but right now they are still at an altitude of 5,300 metres because the lower altitudes are still very hot for this time of the year,” said Thupden Lachungpa, also pointing to the decrease in grazing area due to army presence.

In India, the yak-rearing states include Arunachal Pradesh, Sikkim, Uttar Pradesh, Himachal Pradesh and the former state of Jammu and Kashmir – now split into three union territories of Jammu, Kashmir, and Ladakh. The total yak population in the country stands at 58,000 in 2019, a decrease of 24.67 percent over the previous census in 2012, as per the 20th livestock census.

Pastoral yak rearing system in Sikkim in the eastern Himalayas is changing to cope with climatic changes. Credit: Feroze Sheikh, et al.

The journey

The paper described the current migratory route of the yak in North Sikkim. As spring sets in around mid-February to April, the herders in Lachen and Lachung valleys start their sojourn upwards towards cooler pastures along with their yaks.

The yaks graze at sub-alpine pastures at altitudes of 3,000 to 4,000 metres in Zeema, Samdong, Yathang, Yaksee, Seemba, and Yumthang, which improves their body condition. This is the period when calving and milking starts. It peaks from May to September in the summer.

In this season, the herders along with their yaks move further up, around 4,000 to 5,000 metres, due to a shortage of pasture lands in lower altitudes and because the yaks can’t endure high temperatures.

With the advent of autumn during mid-September-October, yaks start their downward journey. This time, the animals graze on temperate pasture at lower to mid-elevation, 3,000-3,600 metres, and they still remain productive.

During December-February, they return to the relatively warmer pockets closer to the villages near Lachen and Lachung at altitudes of 2,750 metres to 3,000 metres.

Shift in seasons

In the past two decades, the region has experienced an increase in annual temperature by 0.03 to 0.04 degree Celsius and receding snowfall. The timing of snowfall has shifted from November to December and January to March, said study author Sheikh Mohammad Feroze of Central Agricultural University, Imphal, Manipur.

The shift in seasons has caused a shift in the trans-humans practice: the start of upward migration of yak herders has advanced by 15-30 days due to a rise in March temperatures and the span of migration has also extended by about 30-45 days, the study notes.

“The downward migration is restricted to mid-elevation – 2,750 to 3,000 metres – now due to an increase in temperature, which was earlier about 2,000 metres, whereas the upward migration has gone up farther about 500 metres,” said Feroze.

Between December 2018 to May 2019, 300 yaks starved to death in Muguthang and Yumthang in north Sikkim district. Newspaper reports quoted locals saying that while snowfall had thinned over the decade, the 2018-2019 season’s snowfall was relatively heavy leading to starvation of the animals.

Rising yak deaths

Yak herders in Lachung and Lachen also associated soaring mercury to rising yak deaths from liver disease, in which the organ becomes black in summer season. “Moreover, pregnant...[yaks] sometimes die in the summer as they cannot survive in a warm climate. Protozoan parasitic diseases, hoof and mouth disease, and skin disease are on the rise...[owing] to comparatively conducive climatic conditions than earlier,” the study said.

Yaks cannot tolerate temperatures above 15 degrees Celsius. Warming climate is causing diseases and death in yaks in north Sikkim. Credit: Feroze Sheikh, et al.

While the yak herders quizzed in the study area were not certain about any change in milk yield, as the very low level of milk yield of yak made it difficult for them to detect any marginal change in the yield, studies have linked elevated temperatures to reduced milk yield, according to the authors. This is because milk production takes a hit when the quantity and quality of the forage or alpine pasture deteriorate due to rising temperatures. Moreover, the number of hybrids between the yak and a cattle that are comparatively high yielders has gone up in the herds over the years, they add.

Engaging local communities

The authors suggest consulting and engaging the Dzumsa and the community and integrating the local knowledge base into science-based policy decisions and implementation process. For example, financial resources for activities such as the construction of sheds for the yaks and provisioning of feed supplement activities can be drawn as one-time support from the developmental schemes run by the local administration.

Rejuvenation of pasture is a mammoth task and it requires community consensus. So scientific organisations and the community may be consulted by Dzumsa to decide upon the types of grasses and fodder trees suitable for different altitudes and the methods of pasture rejuvenation, recommend the authors.

The authors also warn against indiscriminate hybridisation which may lead to the die-out of pure breed. “Herd diversification may be promoted as an alternative strategy to cope up with any risk to income due to climate change. Dzumsa in collaboration with scientists and subject matter specialists should conduct awareness camps about climatic change effect on yak farming and available strategies for the yak herders as well as owners,” the authors add.

According to animal physiologist, Vijay Paul, who works extensively on yaks, one of the biggest challenges is to keep the younger generation engaged in yak husbandry because of the hardships encountered in rearing them.

“So we advise the communities in Arunachal Pradesh, Sikkim, and Ladakh to keep the animals at different altitudes in good quality pastures and to avoid continuous migration so that yak rearing can be linked to ecotourism,” said Vijay Paul, principal scientist for animal physiology at ICAR-National Research Centre on Yak.

This article first appeared on Mongabay.