Abstract <p>Our study is devoted to the foraging strategies of the sympatrically nesting Glaucous gull (<i>Larus hyperboreus</i>) and Vega gull (<i>Larus vegae</i>) in two locations at two locations in Chaun Bay, East Siberian Sea. These gull species nest both in colonies and in solitary pairs and use similar foraging methods: scavenging, foraging, and active predation on eggs and chicks. Anthropogenic food sources are prioritized by both species. Birds are the second most important food source for the Glaucous gull and isopods for the Vega gull. Differences in the diet between gull breeding in colonies and gulls breeding in solitary pairs are more substantial than differences in the food spectrum between different species with the same nesting strategy. This pattern is especially noticeable in the Vega gull. Solitary pairs of both species cannot make long foraging trips, and they forage in close vicinity to their nests using other bird species as prey (a stable available resource in the nesting habitat). Colonial gulls forage mostly at dumps (a stable resource but located far away from the nesting sites).</p>