Coupled effects of climatic forcing and the human footprint on wildlife movement and space use in a dynamic floodplain landscape

Abstract

With climate change, terrestrial fauna in riparian floodplain ecosystems must adapt to a predicted increase in frequency and magnitude of fluvial perturbations. Seasonal migration to seek refuge from floodwaters represents a central adaptation strategy, but may entail risky navigation of anthropogenic spaces in heterogeneous landscapes. Here, we demonstrate the opportunities and constraints large-bodied mammalian herbivores face during an adaptive response of obligatory flood-driven refuge migration, across a human-dominated environment. Our study system, centred around a productive protected area––Kaziranga National Park in Assam, Northeast India––on the floodplains of the Brahmaputra River, is home to an abundance of large herbivores that undertake seasonal migrations in response to floods. We contrast species distribution data during a major flood event with those from the dry season to illustrate season-specific movement and space use decisions of large herbivores ranging in body mass from the 3000-kg Asian elephant Elephas maximus to the 20-kg muntjac Muntiacus muntjak. In the dry season, most large herbivores––a majority of which are endangered and threatened by anthropogenic pressures––avoided areas with a strong human footprint, while preferring spaces with high land-use diversity. During the floods, such species were pushed out of inundated habitats within the protected area, and they chose to move through woodlands and areas under bamboo cover on private lands, as they migrated to forested refugia on higher ground. Our results show how seasonal environmental constraints shaped by floods determine the internal motivation of animals to risk traversing a human-dominated space to seek refuge, which contextually defines how animals view and navigate the landscape. Such insights underscore the importance of dynamic and adaptive planning, and participatory conservation efforts, to facilitate connectivity in the changing environment and climate of the present Anthropocene.