The Aleutian Islands are a chain of 14 large volcanic islands and 55 smaller islands. Most of the Aleutian Islands belong to the U.S. state of Alaska, but some belong to the Russian federal subject of Kamchatka Krai. They form part of the Aleutian Arc in the Northern Pacific Ocean, occupying a land area of 6,821 sq mi and extending about 1,200 mi westward from the Alaska Peninsula toward the Kamchatka Peninsula in Russia, and act as a border between the Bering Sea to the north and the Pacific Ocean to the south.
The Aleutians are home to many large colonies of seabirds. Buldir Island has 21 breeding seabird species, including the Bering Sea-endemic red-legged kittiwake. Large seabird colonies are also present at Kiska, Gareloi, Semisopochnoi, Bogoslof, and others. The islands are also frequented by vagrant Asiatic birds, including the common rosefinch, Siberian rubythroat, bluethroat, lanceolated warbler, and the first North American record of the intermediate egret.
The habitats of the Aleutians are largely unspoiled, but wildlife is affected by competition from introduced species such as cattle, caribou, and foxes. Nearly all of the Aleutians are protected as part of the Alaska Maritime National Wildlife Refuge and the Aleutian Islands Wilderness.
Observations have identified sea otters as a keystone species along the coasts of many of the Aleutian Islands. Their presence encourages the growth of kelp forests, as the otters control sea urchin populations,