It is well established that once birds have laid their eggs they sometimes incubate non-egg objects. However, reports of birds incubating solely non-egg objects (without prior manipulation by researchers) are rare. Here we report on our observation of a Long-billed Dowitcher Limnodromus scolopaceus incubating a clutch composed entirely of mammalian bones. To our knowledge, this is the first report on (a) incubation of foreign objects in Scolopacidae, (b) incubation of a ‘clutch’ composed entirely of bones, and (c) incubation of foreign objects in a nest atypical for this species in both construction and nest habitat. We discuss possible explanations for this presumably maladaptive behaviour.