ABSTRACT Legacies of imperial frontier-making, ongoing border conflicts between nuclear armed nations, changing livelihoods, and the impact of anthropogenic climate change have created complicated claims on Himalayan borderland areas in the name of conservation, security, ethnic identity and development. Combining historical research with ethnography, this article traces the role of the Black-necked crane (grus nigricollis) in the formation of mid-nineteenth century imperial frontiers in the Himalayas and, subsequently, its present-day position in the political ecology of two Himalayan regions along the Sino-India border – Ladakh and Arunachal Pradesh. We introduce the concept of ‘border object’ and demonstrate how it can serve as a useful concept to understand how non-humans become participants in changing configurations of territoriality, biopolitics and science, which underpin both a past imperial frontier and present-day border regimes.