Throughout his oeuvre, Amitav Ghosh deals with storytelling and migration. Exploring legacies of empire and entanglements between the human and non-human world, his writing is driven by an ethical imperative to excavate “forgotten” stories, and, especially in his later texts, to find new forms of storytelling suited to capture pasts, presents, and futures shaped by a growing sense of planetary crisis. Gun Island (2019), a generic mix of personal quest narrative, thriller, romance, and folk tale, depicts a world disrupted by different forms of multispecies migration. Linking the Indian subcontinent, the US, and Europe, it chronicles voluntary and forced journeys of humans and animals between the Global North and South, intertwining refugee and climate crises in the Mediterranean and Bangladesh with the morally charged legend of the gun merchant, a seventeenth-century world traveller. The text brings current and historical links between migration and climate change, which are comparatively rarely treated in literary fiction, into sharp focus. As this essay argues, it highlights specifically the need to broaden the notion of migration literature and its subgenres to include both human and animal migration and the impact of globalization and current realities of climate change. Exploring genre and poetics in Gun Island, this essay reads the novel against the broader aesthetic and cultural-historical arguments made in Ghosh’s The Great Derangement (2016) and The Nutmeg’s Curse (2021). To explore Ghosh’s poetics, which fuse everyday realism with the uncanny, the improbable, and the mythical, this essay also draws on Thom van Dooren and Deborah Bird Rose’s notions of “ethography”. It argues that Gun Island, as a multispecies climate migration novel, responds to the author’s call for a rediscovery of storytelling beyond Western-style realism or SF, as a means to capture human and non-human subjectivities and to undo demarcations between rationality and spirituality.