To get to know streaked ­sparrows, focus first on a few key features of the face

Why a duck’s head shape might vary from the picture in your field guide

How your line of sight can change how dark or pale a bird’s feathers appear

To learn bird songs, listen carefully while watching the accompanying behavior

How to use body shape to identify songbirds whose field marks aren’t visible

How the Red-winged Blackbird makes its patches obvious one minute and almost invisible the next

Why you should be cautious about judging color based on fleeting views

How the way a bird holds its legs in flight can change its ­appearance

Why bill color remains an important field mark for identifying Caspian and Royal Terns

How to use proportion, shape, and pattern to ID Cooper’s and Sharp-shinned Hawks

Paying attention to differences in behavior can help you recognize different subspecies