Birds are defined as vertebrates – animals with backbones – that have feathers and wings. They don’t have to fly to be considered a bird, but they all have wings. Reptiles are a separate group.

Nature has a few rules to help explain the extreme shapes and sizes we see in the animal kingdom. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it ...

You can already use one kind of AI-powered analysis with Merlin, a free app from the Cornell Lab of Ornithology that identifies bird species. To identify a bird by sound, Merlin takes a user’s ...