The accelerating decline of birds is a bellwether of far deeper biodiversity crisis — one that threatens not only beloved species but the humans who live alongside them.

Scientists studying data collected over more than three decades found accelerating losses. Their research offers clues about the causes.

What Does a House Sparrow Look Like? The male house sparrow has a gray and rusty crown with pale cheeks and a black bib. Reader Patrice Iacovoni of Waterford, Michigan, shared a photo of a female ...