Forbes contributors publish independent expert analyses and insights. I write about biodiversity and the hidden quirks of the natural world. There’s an important concept in evolutionary biology called ...

1. Passenger pigeons have been extinct for more than 100 years. At one time, huge flocks of these birds darkened the sky as they moved around eastern North America. 2. Only six dusky seaside sparrows, ...

The bird is of cultural significance to the Māori people of New Zealand, and its numbers are starting to increase again.

EDITOR’S NOTE: Call to Earth is a CNN editorial series committed to reporting on the environmental challenges facing our planet, together with the solutions. Rolex’s Perpetual Planet Initiative has ...