Chimpanzees, dung beetles and seed dispersal: implications for habitat conservation of the West African chimpanzee Pan troglodytes verus in Taï National Park, Côte d'Ivoire

Seed dispersal is a key stage in the life cycle of plants, thus in forest regeneration, especially in the tropics. Chimpanzees are known as important seed dispersers and dung beetles play critical roles in secondary dispersal thus increasing the chance for seed post-dispersal success. Hence, understanding secondary seed dispersal by dung beetles is critical to our understanding of forest dynamics. The aim of this study was to evaluate the effects of successive dispersal by chimpanzees and by dung beetles on the surface dispersal and burial of the seeds of four plant species: ( Dacryodes klaineana (Pierre) H.J. Lam, Diospyros mannii Hiern, Pycnanthus angolensis (Welw.) Warb. and Uapaca guineensis Muell) at three nesting site in the Taï National Park. To investigate this, 28 seeds i.e. seven seeds per plant species (N = 75, average ± SD: 28.24 ± 3.06 seeds) were introduced into 85 g of chimpanzee faecal matter. This set was exposed on the forest floor for 48h following an average faecal radius of 5 cm (N = 40, average ± SD: 5 ± 1.06 cm). From the observations made, it emerges an essentially surface dispersion, ie 45.6% of the seeds dispersed against 6.3% of seeds buried. The highest rate of vertically dispersed seeds, ie 10.31%, and average depth of burial, ie 7.45 cm, were quantified in the southern nesting sites. This distribution of seeds would not only be linked to the time of deposition of the faecal matter, but also and above all to the size of the secondary disperser.