The large skuas, formerly Catharacta, are a taxonomic problem of great proportions, and also an identification nightmare. There are various southern skua populations that differ in size and coloration, although in various cases hybridization is not uncommon. It is akin to the problem of large Larus gulls in the northern hemisphere. In many respects the Chilean Skua is unique. It is the only one that has a strong rusty tinge to the plumage, usually solidly rusty on the underwing linings and sometimes throughout the underparts, being strongest on the throat. Some immature ages when worn can have little or reduced rusty, and are misidentified as Brown Skuas (Stercorarius antarcticus). Chilean Skuas are usually clearly dark-capped, and their central tail feathers are often longer than that seen in other large skuas, two features that suggest “jaeger tendencies” in the appearance of this skua. The real differences are in its behavior, it is the only southern Skua that typically nests in colonies, like a gull! Although they are kleptoparasitic, as well as voracious predators, Chilean Skuas also catch a sizeable portion of their food in an “honest” manner. Again, more gull like than other skuas. Chilean Skuas nest throughout southernmost Chile and Argentina, and there is a narrow area of hybridization along the Chubut – Santa Cruz coasts in Argentina. They are migratory and reach Brazil and Peru in the non-breeding season, many of these northern migrants appear to be immatures. These northern migrants are pelagic, although ill or undernourished individuals often show up looking bedraggled on northern beaches.