Rare vagrant birds can be a challenge to identify correctly. In many migratory bird groups (e.g. waders, terns, and petrels), several species look very similar to each other. There are further complications with species that look very different depending on their age and breeding status (e.g. juvenile plumage versus adult non-breeding plumage, or adult breeding plumage). When a previously unrecognised vagrant species reaches New Zealand, it is even more challenging, as it will not be featured in New Zealand field guides and websites. Unless bird-watchers are thinking globally, a previously unrecorded species may be overlooked if it is misidentified as a species that is already on the New Zealand list. Curator Vertebrates Colin Miskelly describes how this was the initial fate of New Zealand’s first black tern.