This chapter explores metamorphosis by focusing on the so-called ‘shearwaters of Diomedea’ – a group of seabirds whose odd behaviour recalls their previous existence as humans. It puts these birds in conversation with other humans-turned-animals both ancient and modern and investigates how they reflect on the experience of transformation. The chapter reveals that both ancient and modern tales of metamorphosis draw on the notion of hybridity in so far as many of the creatures undergoing such a transformation are, in effect, hybrids: they retain part of their human identity while also sporting the body of an animal. At the same time the chapter points to an important difference between ancient and modern ways of thinking the human. It shows that modern tales of metamorphosis tend to explore the dissolution of the boundary that separates the human from all other animals. The ancient conversation, by contrast, returns to – and ultimately affirms – the positions of some of the Greek philosophers arguing for an essential human difference.