Koniuji Island provides nesting habitat for close to 300,000 seabirds. Around 70% are Fork-tailed Storm-petrels and 17% are Leach's Storm-petrel. There are also large numbers of the Ancient Murrelet and the Whiskered Auklet that nest on Koniuji. These four species breed on Koniuji Island in numbers that exceed 1% of their total global populations.