Growth of the nesting colony of slaty-backed gulls (Larus schistisagus) and plant cover degradation on Shelikan Island (Taui inlet, the Sea of Okhotsk)

Abstract

The size of Larus schistisagus nesting colony on Shelikan Island (8 ha in area) has increased from 2000 to 6000 pairs over 18 years. Today, this is the largest colony in the Sea of Okhotsk. The growth of the bird population has entailed catastrophic deterioration of the plant cover accompanied by a decrease in the species diversity of vascular plants: more than one-third of plant species recorded on the island in 1986 have already disappeared, and the establishment of several new plant species cannot compensate for this loss. If the size of the colony increases further, woody vegetation will fully deteriorate and only a thinned herbaceous layer consisting of 15–20 most resistant species will remain on the island.