When fisheries biologist James Drymon noticed feathers in the vomit of a tiger shark, he first assumed they belonged to some unfortunate seabird: a gull, perhaps, or a pelican. But when he and his team genetically sequenced the feathers, the results surprised them: the quills came from a land-based songbird called a brown thrasher. So what was it doing in a tiger shark's stomach in the Gulf of Mexico?