Loons are similar on the water, but lack hooked bills. Most loons hold their bills level while swimming while cormorants hold theirs angled upwards. All adult cormorant species in the U.S. are separable by the shape and color of the gular areas. No other species has a small red gular region. The Pelagic Cormorant shares its Pacific Coast range with the Double-crested and Brandt's Cormorants. Adult Double-crested Cormorants have orange gular regions and Brandt's have yellow-bordered blue ones. Immature Double-cresteds and Brandt's have paler underparts than the Pelagics. The Pelagic Cormorant is noticeably smaller and slimmer than the other species. The Red-faced Cormorant overlaps the range of the Pelagic Cormorant only in Alaska. In the breeding season, the Red-faced Cormorant has a red forehead and a pale bill.
Length and wingspan from: Robbins, C.S., Bruun, B., Zim, H.S., (1966). Birds of North America. New York: Western Publishing Company, Inc.