BIRDS, AS THE SAYING GOES, are what they eat. And knowing exactly what they eat can help conservationists protect critical food sources and track environmental change. But until recently, sussing out birds’ grocery lists was cumbersome, requiring close observation to determine which type of berry a songbird snatched up or what kind of fish dangled from a seabird’s bill.
Biologists are increasingly turning to genetic tools to eliminate the guesswork of figuring out avian fare. They’re building upon methods that scientists have employed for the past decade to solve other ecological unknowns,
