Diet of Free Ranging American Mink (Neovison vison) in Denmark

SIMPLE SUMMARY: This study is the first to compare the diets of captive-born (escaped farm mink) and wild-born mink. This study aimed to evaluate the diets of captive-born and wild-born mink and compare the diets of mink on mainland Denmark and the seasonal variations in diet. The stomachs of 243 wild-born and 114 captive-born mink were analyzed. No significant differences were found between the diets of captive-born mink and wild-born mink from the two populations (mainland Denmark and Bornholm). Significantly more empty stomachs were found during spring than during the summer and autumn. Primarily, the diets of the mink consisted of fish, voles, birds, and crustaceans. ABSTRACT: Non-native American mink (Neovison vison) is a widely spread predator in Denmark. The feral population in mainland Denmark consists of captive-born mink that escaped from fur farms and wild mink born in nature, whereas the population on Bornholm is almost all wild-born mink. In this study, the diets of feral mink in mainland Denmark and on the island of Bornholm are analyzed. The aim of this study was to examine (1) whether the diet of the larger captive-born mink differs from that of the smaller wild-born mink, (2) assess the regional variations between the diets of mink in mainland Denmark and on Bornholm, and (3) investigate the seasonal variation in the diet composition of mink. The stomach contents of 364 mink (243 wild-born and 114 captive-born) culled in the years 2019–2022 were analyzed. Of these, 203 mink were from mainland Denmark, and 154 were from Bornholm. No significant differences were found between the diets of captive-born mink and wild-born mink or the mink found in mainland Denmark and on the island of Bornholm. Significantly more empty stomachs were found during spring than during the summer and autumn, suggesting a bottleneck in the diet during spring.