Frugivorous primates in temperate and subtropical regions often experience a shortage or complete absence of fruits for several months of the year. We studied the foraging ecology of a group of stump-tailed macaques in a subtropical forest during winter, when fruit abundance was low. We conducted this study in the Hollongapar Gibbon Sanctuary, Assam, India, from December 2015 to April 2016. We estimated the time-activity budgets, diet, and habitat use of the study troop and also conducted vegetation sampling and phenological monitoring of the study area. The stump-tailed macaque troop spent about 73.2% of its time foraging and feeding, with seasonal differences in food species intake and in habitat use. Open degraded forests were primarily used in December, January, and February, when the macaques largely fed on shoots of the bamboo and roots of the herb , while they mostly utilised in canopy-covered, degraded forests in March and April. There was a major shift from a primary diet of fruits in the wet season, reported from earlier studies, to possibly relatively poorquality, but abundant, shoots and roots in winter. This suggests that the consumption of these poor-quality fallback food species is a key dietary adaptation of the macaques to periods of fruit scarcity. Although our preliminary study suggests that the feeding behaviour of the stump-tailed macaque in its subtropical semievergreen forest habitat appears to be similar to that of its congeneric species in temperate forests, further investigations are needed to firmly establish the observed foraging patterns of this vulnerable cercopithecine species in its last lowland rainforest refuge in northeastern India.