To tell the sex of a Galápagos penguin, measure its beak, researchers say

For a Galápagos penguin, beak size is nearly a perfect indicator of whether a bird is male or female, scientists have discovered. Armed with this knowledge, researchers could determine the sex of a bird quickly and accurately in the wild without taking a blood sample — speeding up field studies of this unusual and endangered seabird.

Source: sciencedaily.com