Post-breeding movements of Pink-footed Geese on Svalbard have been described for failed and non-breeders, and show that the geese move east and north before moult, presumably avoiding competition with breeders (i.e. in the west) and exploiting areas with later phenology and thus higher food quality. However, for breeders, post-breeding movements are not well-studied even though geese stay on Svalbard 1.5 months after the chicks fledge. We caught groups of breeders and tagged 35 female Pink-footed Geese with GPS-GSM neckband transmitters, in two areas: Longyearbyen (southeast of Isfjorden) and Daudmannsøyra (northwest of Isfjorden). We found that these geese used two main post-breeding routes: via Edgeøya in the east, and via the western Nordenskiöld Land and South Spitsbergen. However, the birds from the western tagging location mainly used the eastern route, and those from the eastern location mainly used the western route. We think that local geography explains this pattern, because geese from Daudmannsøyra moved mainly along the north coast of Isfjorden towards the east, thereby ending up in the valley of Sassendalen that leads them to the east. Geese that migrated east, from both areas, were later in their moult cycle during our catches. In the group from Longyearbyen, those geese that took the eastern route had more chicks. Nevertheless, geese on the eastern route left almost a week earlier for over-sea migration than geese taking the western route. We test if this is a constraint (i.e. does winter start earlier in the east due to the influence of the Arctic Ocean?) or facilitated by a higher food quality in the east (as suggested by the elevation of the areas that the geese actively visited, and by CN-ratio of droppings). These findings suggest that local geography plays an important role for post-breeding movements of Pink-footed Geese on Svalbard.
|Status||Gepubliceerd - 26 mrt. 2019|