Marked differences in foraging area use and susceptibility to predation between two closely-related tropical seabirds.

Ecological theory predicts that closely-related species must occupy different niches to coexist. How marine top predators achieve this during breeding, when they often gather in large multi-species colonies and are constrained to central-place foraging, has been mostly studied in productive temperate and polar oceans with abundant resources, but less so in poorer, tropical waters. Here, we track the foraging movements of two closely-related sympatric seabirds-the white-tailed and red-tailed tropicbirds Phaethon lepturus and P.