Identifying birds in flight can be a tremendous challenge, but birders who know the parts of a bird's wing can more easily pick out clues to properly identify the species. Both the structure of the wing and the types of wing feathers can be crucial field marks, and they can be easy to learn.

Wing Structure

The structure of the wing can be a fantastic way to help identify the species. Check these five clues to help puzzle out which bird is flying by.

• Wingspan: The combined length of both wings from wingtip to wingtip can be a vital identification clue. Ideally, judge the wingspan when the bird is holding its wings level so there is no distortion, and consider the complete length across the bird's body. If possible, judge the length by other birds or nearby objects for a more accurate assessment.
• Wingtip: Wingtips are easily visible on flying birds, and determining if they are rounded or pointed can help with proper identification. Another clue can be the splay of the primary feathers, how wide the spaces are between each individual feather on the wingtip. Some birds hold these feathers close together while others spread them more drastically.
• Wrist: The bend of a bird's wing is its wrist, and how that wrist is held can distinguish different species. As with wingspan, it is best to make this judgment when the bird's wings are fully extended and the bird is gently soaring, so the wing is at a rest position. Check if the wrist joint is relatively straight or shows a stronger bend, and how that bend compares to the position of the head. At the same time, check for any markings, such as a dark patch or comma-like shape at the wrist.

• Patagium: The leading edge of the wing is the patagium, and its color can help identify a bird, such as the dark patagium on the red-tailed hawk pictured above. Check if the whole patagium is colored or if it is simply splotched or speckled.
• Wingpit: A bird's wingpit is the equivalent to the human armpit, the area close to the body on the interior of the underside of the wing. This area can show distinct colors or markings vital for bird identification. Look for streaks, barring or color patches on any in-flight bird you're trying to identify.

Wing Feathers

While the structure of the wing is often more immediately useful for field identification, field guides often refer to different types of feathers when listing key field marks. Understanding how those feathers look on a wing can help you be prepared to identify each bird you see.

• Primary Feathers: The primary feathers are the "fingertip" feathers of the wing and are found at the wingtip.
• Secondary Feathers: Secondary feathers make up the back edge of the wing closer to the body. They are generally shorter and closer together than primaries, and birds do not manipulate them as much as they do their primary feathers.
• Coverts: Covert feathers make up the wingpit as well as the upperside of the wing and cover the base of the primary and secondary feathers. They may be called primary coverts or secondary coverts depending on which feathers they are aligned with.

Not every bird will show unique identification clues on every part of the wing or every type of wing feathers. Understanding the possible markings, however, is important to be prepared to identify every mystery bird that flies by.

Learn how the parts of a bird's wing appear different on a perched bird!

Photo – Red-Tailed Hawk © Franco Folini

A perched bird shows a much different, and less helpful, view of its wing than a bird in flight. The same wing feathers can be seen on perched birds, however, even though most of the structural wing parts that are useful for identification are hidden. The patagium, wrist, wingspan and wingpit cannot be seen properly for identification on perched birds, but the types of wing feathers can still be informational.

• Primary Feathers: The primary feathers make up the longest part of a bird's folded wing and culminate in the wingtip. When the bird is perched, different edging colors are more visible on these feathers, and the primary projection – how far the primary feathers extend beyond the secondary feathers – can be a great clue for identifying tricky bird species.
• Secondary Feathers: The secondary feathers are less visible on a folded wing and are closer to the bird's back, though they can overlap significantly and may not be easily seen. As with the primary feathers, look for edge colors that may be visible and could provide a clue for identification.
• Coverts: Both the primary and secondary coverts on the upperside of the wing are easily visible on perched birds. These feathers make up the forward part of the folded wing, and their edging or colored tips can create wing bars that are ideal field marks.

Understanding the basics of bird wing anatomy is a great way to sharpen your bird identification skills.

Because wings are so very important to birds, it is essential that birders know how to use those wings to help their identifications take flight.

Photo – Yellow-Rumped Warbler © Dan Pancamo