Key words: American Mink, predator control, seabirds, coastal Norway, biodiversity
Abstract
The introduction of the non-native American Mink Neogale vison (syn. Neovison vison), a predator of birds and their chicks and eggs, is one of many anthropogenic factors that may be driving the decline of seabird populations in areas where mink are prevalent. Previous studies have shown that ground-nesting birds utilising coastal ecosystems are especially vulnerable. In this study, we investigated changes in seabird and coastal-bound bird populations, focusing on ground-nesting species, and the potential effect from mink culling. Ten locations in the archipelago of Flatanger, a coastal municipality in central Norway, were surveyed, and bird counts from 1991, 2016, and 2023 were compared. A total of 247 mink were trapped and removed from 2015 to 2023 because of a bounty hunting program initiated by the government. The study found that the abundance of most avian species decreased from 1991 to 2016. However, from 2016 to 2023, diversity (Shannon diversity index, H') increased significantly, and a greater number of ground-nesting species were observed overall. Notably, numbers of terns, including the Common Tern Sterna hirundo and Arctic Tern Sterna paradisaea, decreased dramatically from 1991 to 2016 but showed the largest increase of any species between 2016 and 2023. Terns are particularly sensitive to mink predation. Our results suggest that incentivizing local hunters to trap mink may have contributed to an increase in local faunal diversity. However, further research and targeted management strategies are required to ensure long-term conservation, as the complexity of ecological drivers make it difficult to attribute population declines solely to mink predation. Nonetheless, early indications and the significant increase in H' following nine years of mink culling suggest culling may have contributed to positive ecological changes.
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