Flocks of geese and other birds come to the islands from the north (Bunge and Toll), as also the gull Lestris pomarina, which feeds chiefly on the lemming.
The eastern portion of the island, named Bunge's Land, is thickly covered with Post-Tertiary deposits.
The third theory is that of Bunge, who says that in chlorotic conditions there is an excess of sulphuretted hydrogen in the bowel, changing the food iron into sulphide of iron, which Bunge states cannot be absorbed.