Ectoparasites are common on birds and in their nests. Amongst these parasites are diverse gamasid mite species that can lead to irritation, disease transmission and blood loss. Few studies of the ectoparasites of birds breeding in the High Arctic exist. The parasitic mite, Dermanyssus hirundinis, was found in nests of snow buntings Plectrophenax nivalis nivalis, both natural nests and within nesting boxes, on Spitsbergen. Densities per nest varied from sporadic to greater than 26,000 individuals. This is the northernmost observation of this parasite. The mite was present in new nests, nests constructed the previous year and nests not utilized the previous summer. The parasite survives at least 18 months without access to a blood meal and can tolerate the Arctic winter, surviving temperatures below −20°C. D. hirundinis is hence well adapted to arctic conditions. Only females were observed suggesting that this population is facultatively parthenogenetic.