Effects of Food Availability, Snow and Predation on Breeding Performance of Waders at Zackenberg

The first few weeks after arrival on the tundra in late May and early June appear to be the most critical period in the summer schedule of arctic-breeding waders. Food availability and snow-cover determine population densities and timing of egg-laying, and early egg-laying seems essential, since it increases the chances for re-laying in case of nest failure, optimises timing of hatching of the chicks in relation to the peak period of arthropod food for the young, facilitates early departure of the adults and maximises the time available for the young to grow strong before winter begins in early September. Conditions for waders in most of high-arctic Greenland seem favourable as compared to several other arctic areas, in that the climate is continental with favourable weather conditions during most summers, and the predation pressure on eggs and chicks is normally moderate. With the projected climate change, the waders of high-arctic Greenland may face more unstable breeding conditions, and in the long term some of the wader species may be hampered by overgrowing of the high-arctic tundra withmore lush low-arctic vegetation.