Identifying the behavioural patterns of bone collecting animals is a crucial aspect of taphonomic studies. Although many studies have established criteria for identifying animal-collected or animal-modified bones, very few papers describe the distinguishing features of fox-made bone assemblages. The bone assemblage collected in an inactive underground stone mine in Potok-Senderki (Poland) is diagnostic of a red fox (Vulpes vulpes) den. This site provides an ideal opportunity to develop an understanding of the bone collecting behaviour of red foxes in cave-like environments. This study showed that bones collected by red foxes are concentrated in clusters. The bones represent a broad spectrum of local fox prey species, with most bones showing the marks of gnawing. Each cluster may contain from <10 to >100 bones. Furthermore, the long axes of the bones in clusters frequently show specific orientation. The analysis of bones at this site might make an important contribution towards the establishment of baseline criteria for the identification and evaluation of fox-accumulated bone assemblages. Copyright © 2012 John Wiley & Sons, Ltd.