Yak mortality in free-range grazing systems: A case study in Laya Block, Bhutan

Abstract

Yak farming is economically and culturally vital to highland communities, providing protein-rich products in harsh environments. Despite their resilience, yak mortality presents a serious challenge. This study aims to examine the causes of yak mortality to inform effective management strategies for sustaining this essential species. Data were collected through face-to-face interviews using semi-structured questionnaires via the Epicollect5 mobile application. All 53 herders from Laya Block were interviewed to gather information on mortality causes, herders’ characteristics, and income.

Approximately 94.3% of herders reported yak mortality, with an annual mortality rate of 7.9% and a mean loss of 5.3 yaks per household. Yak mortality is primarily caused by wildlife depredation, which accounts for 58.8% of total proportional mortality. On average, each household loses 3.1 yaks annually to wildlife predation, representing a 4.6% mortality rate relative to the total yak population. The second leading cause is Gid (Coenurosis), responsible for 23.7% of deaths, with an average of 1.2 yak losses per household and a 1.9% mortality rate per total population. Other factors such as winter fodder shortages, accidents, harsh winter conditions, and natural causes contribute smaller shares to the overall yak mortality. However, no significant difference in mortality rates was observed between the two leading causes across age groups (P > 0.05), indicating equal vulnerability and highlighting the urgent need for intervention strategies to mitigate these challenges and promote the conservation of this vital ruminant species in highland communities.