Understanding the factors that influence territorial behaviour is essential for determining whether fragmented habitats are able to support the spatial ecological conditions that maintain cooperative breeding systems of threatened bird species. Here, we examine territorial behaviour of the cooperative breeding Buff-throated Partridge Tetraophasis szechenyii in patchy tree-line habitats of the Pamuling Mountains in western China. This population has been habituated to humans through supplementary feeding by Tibetan Monks. We studied 18 groups during three consecutive breeding seasons and two non-breeding seasons from March 2007 through July 2009, using direct tracking of colourmarked individuals. Territories were occupied by stable family groups, and were centred on the interface of two or more different tree-line habitats. Groups occupied the same close area near the nest from one year to the next. However, territory sizes, estimated using radio-telemetry, were smaller compared to those of other non-cooperative breeding montane Galliformes. Both territory size and overlap were greater during the non-breeding season. Group size did not influence territory size, in either the breeding or non-breeding season. Territorial behaviour was influenced by supplementary food given at two offering sites during both seasons, in proximity to both nesting and roost sites. Further research should focus on examining the interactions between supplementary feeding and family group composition, with direct comparisons of data from non-supplementary fed partridge populations outside of Buddhist Sacred Sites.