Adak Birding Tours Aleutian Outfitters is the only local birding company that offers guided birding tours of Adak Island. Because they operate year round on Adak they specialize in being able to provide custom tours every month of the year. Your guide, Isaac Helmericks, is a third generation Alaskan and he has spent time birding in just about every main location in Alaska.
May and September are normally the "really good" times of year for Asian rarities or other birds only seen during migration. But Adak offers great birding in the other months as well. Summer months can be a great time to see local specialties, and winter months are not your typical birding months but Adak does offer some great birding then too.