Dr. Ajith Kumar left us saddened on 1 March 2025, aged 72, in the Satpura hills of central India, while on a field trip with his students. His last day was spent in the same way he spent more than four decades of his career, walking through a forest in the company of young future wildlifers and a pair of binoculars in hand. He was among India’s foremost wildlife biologists. Born in Kerala on 6 June 1952, he took his master’s degree in zoology at the University of Kerala and his doctorate at the University of Cambridge. Over more than forty years of work on the ecology and conservation of primates and small mammals, across the Wildlife Institute of India, the Sálim Ali Centre for Ornithology and Natural History, the Wildlife Conservation Society and the National Centre for Biological Sciences, he helped shape the discipline of wildlife science in this country. His research on the endangered lion-tailed macaque in the rainforests of the Western Ghats influenced a generation of field ecologists and remains a key reference for work on rainforest fragmentation.