Exploring the potential of brown bear (Ursus arctos arctos) as a long-distance seed disperser: A pilot study in South-Western Europe

Abstract

Plant dispersal is crucial to maintaining plant community dynamics, especially in the current context of rapid environmental changes such as global warming and landscape fragmentation. We seized the opportunity to carry out a pilot study on endozoochorous dispersal by the endangered Pyrenean brown bear. We based our study on faeces collected by the Brown Bear Network and location data from three bears fitted with GPS collars and translocated from Slovenia to the Pyrenees in 2006. We studied 39 faecal samples, 25 of which contained seeds from two to three different taxa. We identified a total of 47 plant taxa, 30 to the genus level and 21 to the species level. The seeds from plants bearing fleshy fruits: Vaccinium myrtillus or uliginosum, Rubus idaeus, Malus sylvestris and Sorbus sp., but also dry fruits: Thymus sp., Betula pendula or alba, were the most frequently recovered. We estimated average distances moved by bears to vary from 0.85 to 1.34 km over a 6-h period, corresponding to the median gut retention time, GRT50% for their berry-based diet in summer and fall. Bears may thus promote the long-distance dispersal of fleshy forest fruits, over longer distances than other sympatric mammals, involved in the dispersal of plants from open areas.