A red knot is a tiny shorebird that makes an epic 9000-mile journey all the way from the arctic to the tip of southern Chile and back. Biologists and nature enthusiasts congregate at various points ...

Crows recently demonstrated an understanding of the concept of zero. It’s only the latest evidence of animals’ talents for numerical abstraction — which may still differ from our own grasp of numbers.

Scientists have been skeptical of claims of mathematical abilities in animals ever since the case of Clever Hans about 100 years ago. The horse, which performed arithmetic and other intellectual tasks ...