At 18.6 square miles (48 sq km), this is the largest of the Diomede Islands located near the corner of the 53-mile-wide (85 km) Bering Strait 26 miles (42 km) east of Cape Dezhnev (65°46'N; 169°03'W). The entire island is designated a Russian border guard outpost and is closed to public access.
The estimated two million crested auklets and one million least auklets make Big Diomede one of the largest colonies for these two species in the North Pacific. There also are substantial numbers of nine other species of nesting seabirds: black-legged kittiwakes, common and thick-billed murres, parakeet auklets, pigeon guillemots, pelagic cormorants, and homed and tufted puffins. Other birds commonly sighted include western sandpipers, rufous-necked stints, Baird’s sandpipers, yellow wagtails, red-throated pipits, northern ravens, common redpolls, snow buntings and Lapland longspurs.
Other notable wildlife: A large walrus haul-out is located on the island’s southwestern shore. Bering Strait is a major migration corridor between the Bering and Chukchi seas for bowhead, gray and beluga whales, Pacific walrus, polar bears and seals.
BirdLife International (2019) Important Bird Areas factsheet: Ratmanova Island. Downloaded from http://www.birdlife.org on 26/04/2019.