High-arctic nesting geese occupying less favourable nest sites are more vulnerable to predation

Abstract

In a simple, rodent-free Arctic ecosystem in Svalbard, we assessed the nestsite characteristics of the main (and highly abundant) migratory herbivore— pink-footed geese (Anser brachyrhynchus)—to determine which nesting geese were preferentially attacked and killed by the only local predator of adult geese, the Arctic fox (Vulpes lagopus). We collected data on goose carcasses and nest-site characteristics at one of the main pink-footed goose breeding areas in Svalbard. Arctic foxes depredated adult pink-footed geese from just over a quarter of the unsuccessful nests in the colony and carcasses were generally found just under 10 m away from a nest. Geese that occupied nests of poorer quality (limited visibility, further distance to forage patches and situated on flatter slopes) and were less well established (indicated by the low degree of fertilization from accumulations of goose droppings) were more likely to be depredated by Arctic foxes. As geese show a high degree of nest-site fidelity and preferentially occupy nests with better protection against depredation and closer to feeding areas, we propose that Arctic foxes targeted, and were more successful in killing younger, more inexperienced or low-quality geese that occupied less favourable nest sites.