Diet of the European bison (Bison bonasus) in a forest habitat estimated by DNA barcoding

Re-introduction of large herbivores is increasingly used as a tool in nature management and for restoration of more biodiverse habitats. This study investigated the diet of recently introduced European bison, Bison bonasus, in a forest habitat in Bornholm, Denmark, with the purpose of evaluating its adaptation to the new habitat and assessing its potential for facilitating development towards a more open and species-rich forest. Metabarcoding of 39 bison dung samples collected during June–August identified 71 plant taxa belonging to 36 families as diet objects, comprising 56% forbs, 20% trees, 17% graminoids and 7% shrubs. The broad composition of the diet shows the capacity of the bison to adjust to new habitats and exploit a variety of different habitats when foraging, including meadows and other wet areas. Among the most frequently consumed plant taxa were the shrub Rubus idaeus, a number of coarse grass species and most tree species found in the habitat. Rubus idaeus were by far the most abundant taxa, constituting 44% of all the DNA sequences. The results suggest that foraging by bison can contribute towards limiting domination by understory shrubs and high, coarse grasses. Over an extended time period, foraging by bison is expected to promote development towards a lower and more open understory and herbaceous layer in the forest habitats.