Valley forests as ecological bottlenecks: Topography and resource concentration structure herbivore use in the Western Ghats

Rakesh Tiwari , Nanda Appaji, Shivashankara Eshwaraiah, Sujeetkumar M Dongre, Mahesh K Patil, Jayanth M Babu, Apoorva Prakash, Sagara Ganesh, Shreeloka S Bennatti, Madhur M Manjunath , Harisha M Nijavvalli, Robert Muscarella, Yogendra Kambalagere

Large-herbivore distributions in the Western Ghats are often interpreted through the perspective of protected areas, forest loss, and human disturbance. This perspective can undermine the ecological role of valley forests and riparian lowlands in steep, human-modified landscapes. Evidence from Asian elephants and other large herbivores indicates that habitat use is shaped by interacting filters of topography, water, forage, and human pressure, with valley systems frequently concentrating accessible resources and movement pathways. In the Western Ghats, dry-season elephant occurrence is strongly associated with rivers and forest cover, while assemblage-level studies show multiple herbivores responding similarly to forest cover, reserve proximity, and human density. These findings support the hypothesis that low-lying forests act as ecological bottlenecks; constrained areas with abundant resources due to topographic conditions. Degradation of valley forests is likely to redistribute herbivore activity toward adjacent agricultural and settlement areas, rather than simply reducing habitat use. We suggest that valley forests and riparian lowlands should be treated as explicit management units in conservation planning and conflict mitigation, while targeted tests using movement data, occupancy models and spatial conflict records are needed to evaluate this mechanism more directly.