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Bird ID Skills

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Size & Shape

Birds are built for what they do.
Every part of the bird you're looking at is a clue to what it is.

The combination of size and shape is one of the most powerful tools to identification. Though you may be drawn to watching birds because of their wonderful colors or fascinating behavior, when it comes to making identifications, size and shape are the first pieces of information you should examine.

With just a little practice and observation, you'll find that differences in size and shape will jump out at you. The first steps are to learn typical bird silhouettes, find reliable ways to gauge the size of a bird, and notice differences in telltale parts of a bird such as the bill, wings, and tail.

Soon, you'll know the difference between Red-winged Blackbirds and European Starlings while they're still in flight, and be able to identify a Red-tailed Hawk or Turkey Vulture without taking your eyes off the road.

Become familiar with silhouettes

Often you don't need to see any color at all to know what kind of bird you're looking at. Silhouettes quickly tell you a bird's size, proportions, and posture, and quickly rule out many groups of birds – even ones of nearly identical overall size. Practice the silhouettes in the carousel at right.

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    Great Blue Heron

    A classic silhouette: long, spear-like bill, elegant S-shaped neck, long legs.

     
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    Great Blue Heron

     
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    Green Heron

    A smaller, more compact heron than the great blue: same dagger-like bill, but shorter, thicker neck and shorter legs.

     
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    Green Heron

     
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    Piping Plover

    Plovers are small, plump shorebirds, with a fairly large, round head and a bill that is always shorter than the head.

     
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    Piping Plover

     
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    Red-headed Woodpecker

    Woodpeckers have long, chisel-like bills and large heads. They have long, stiff tail feathers which they lean against as they hitch around on trees.

     
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    Red-headed Woodpecker

     
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    Barn Swallow

    Swallows are small, graceful songbirds with very long wings, small heads, and small but wide bills. The Barn Swallow’s tail is long and deeply forked.

     
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    Barn Swallow

     
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    Blue Jay

    Jays are large, stout-bodied songbirds with long, full tails and straight, powerful bills. Blue Jays (and Steller’s Jays) have a prominent crest.

     
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    Blue Jay

     
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    Northern Cardinal

    A medium-sized songbird with a long tail, pointed crest, and a short, thick beak perfect for crushing sunflower seeds.

     
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    Northern Cardinal

     
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    American Robin

    Watching this common backyard bird is a great way to learn the typical thrush shape: small, round head, thin straight bill, fairly long legs, and long, slender tail.

     
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    American Robin

     
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    Red-winged Blackbird

    Blackbirds (and relatives orioles, meadowlarks, and cowbirds) are medium-sized songbirds with fairly large, flat heads and a long, triangular bill.

     
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    Red-winged Blackbird

     
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    Western Meadowlark

    Meadowlarks are plumper and shorter-tailed than their blackbird relatives, but they still have the blackbird’s characteristic long, slender, but thick-based bill.

     
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    Western Meadowlark

     
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    Prairie Warbler

    Warblers are small, slim songbirds with fairly large head, short wings, and slender tail. Their bills are slender, pointed, and straight.

     
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    Prairie Warbler

     
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    American Tree Sparrow

    Sparrows are roughly the same size as warblers but tend to look plumper, and their bills are much shorter, thicker, and more powerful.

     
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    American Tree Sparrow

     

Silhouettes are so useful because they help with the first step in any identification: deciding what kind of bird you’ve got. Once that’s done, you’ve narrowed down your choices to one small section of your field guide.

Beginning bird watchers often get sidetracked by a bird’s bright colors, only to be frustrated when they search through their field guide. Finches, for example, can be red, yellow, blue, brown, or green – but they’re always shaped like finches. Learn silhouettes, and you’ll always be close to an ID.

Judge size against birds you know well

Size is trickier to judge than shape. You never know how far away a bird is or how big that nearby rock or tree limb really is. Throw in fluffed-up or hunkered-down birds and it's easy to get fooled. But with a few tricks, you can still use size as an ID key.

  • Familiar Birds, American Goldfinch, Evening Grosbeak

    Sizing Up Finches

    Size can sometimes help with similarly colored birds. A yellow-and-black finch that's smaller than a House Sparrow is probably an American Goldfinch. Evening Grosbeaks have similar colors, but they're almost the size of a robin.

  • Familiar Birds, Downy Woodpecker, Pileated Woodpecker

    Woodpeckers: Small, Medium, or Large?

    Woodpeckers range in size from the big-as-a-crow Pileated Woodpecker to the Downy Woodpecker, which is barely larger than a sparrow.

  • Familiar Birds, Cedar Waxwing, Blue Jay

    Filling in the Gaps

    Sometimes you need two reference birds for comparison. A Cedar Waxwing is bigger than a sparrow but smaller than a robin. A Blue Jay is larger than a robin but smaller than a crow.

Compare your mystery bird to a bird you know well. It helps just to know that your bird is larger or smaller than a sparrow, a robin, or a crow, and it may help you choose between two similar species, such as Downy and Hairy woodpeckers or Sharp-shinned and Cooper’s hawks.

Judge against birds in the same field of view

Your estimate of size gets much more accurate if you can compare one bird directly against another. When you find groups of different species, you can use the ones you recognize to sort out the ones you don’t.

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    Benchmark Birds

    As soon as you’ve learned to recognize a few familiar birds, you can start using their sizes to measure birds you don’t know. These three common shorebirds – the colorful Ruddy Turnstone, tall Willet, and tiny Sanderling – are a great place to start.

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    Stand Out in a Crowd

    Use size and shape to find the full range of species hiding in a large flock. Amid all these orange-billed Royal Terns are a handful of much smaller Sandwich Terns. If you keep looking, you’ll also notice a giant Herring Gull in the background, as well as several smaller Laughing Gulls to the right and behind it.

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    Line Up the Usual Suspects

    A mixed group of gulls can be a real advantage when you’re making identifications. Here, the enormous Great Black-backed Gulls make the few Herring Gulls behind them seem almost dainty. You almost don’t even notice the rarity, a tiny Black-headed Gull from Europe, down in the front row.

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    Size and Shape in Flight

    Size and shape can be very useful for birds in flight, even for large, unruly flocks. Grackles, blackbirds, cowbirds, and starlings often flock together, but you can learn to tell them apart quickly. In this photo, look for short-tailed, sharp-winged European Starlings among the large, long-tailed Common Grackles.

For instance, if you're looking at a gull you don't recognize, it’s a start to notice that it’s larger than a more familiar bird, such as a Ring-billed Gull, that's standing right next to it. For some groups of birds, including shorebirds, seabirds, and waterfowl, using a known bird as a ruler is a crucial identification technique.

Apply your size & shape skills to the parts of a bird

After you've taken note of a bird's overall size and shape, there's still plenty of room to hone your identification. Turn your attention to the size and shape of individual body parts. Here you'll find clues to how the bird lives its life: what it eats, how it flies, and where it lives.

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    Pelican

    Let’s start with an easy one. The pelican’s nearly foot-long fish net of a bill is a good reminder of the dazzling variety of bill shapes in the bird world.

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    Hummingbird

    Hummingbirds use their long, slender, sometimes curved bills to get at nectar hidden deep inside flowers.

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    Pigeon

    Pigeons have surprisingly short bills for such large birds. They mainly use them for picking up small seeds and swallowing them whole.

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    Woodpecker

    Most woodpecker bills are straight, strong, and sharp, helping the birds drill into wood and pry apart bark.

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    Woodpecker

    Northern Flickers have unusual bills for woodpeckers. Their slightly arched bills help them dig into the ground after ants, a major food source.

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    Chickadee

    Chickadee bills are short, stubby all-purpose tools used for delving into crevices and cones, catching insects, and hammering at seeds.

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    Nuthatch

    Though nuthatches are similar in size to chickadees, their bills are much longer and more pointed – better for prying and pecking.

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    Wren

    Wren bills are long, very slender, and often slightly curved.

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    Flycatcher

    Flycatchers have broad, flat bills surrounded by bristle-like feathers that help them catch insects on the wing.

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    Thrush

    Thrush bills are straight and pointed, used for catching insects or plucking berries.

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    Thrasher

    Thrashers have long bills that can be strongly curved. They use them to flick aside leaves in the understory looking for insects.

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    Shrike

    Shrikes are remarkable songbirds that catch lizards, insects, and small mammals. Their strongly hooked bills reflect their carnivorous lifestyle.

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    Vireo

    Vireos are small birds seen among leaves and tree branches. They often look like warblers, but their bills are thicker and very slightly hooked.

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    Warbler

    Warblers have straight, slender, pointed bills that they use to grab caterpillars and other insects from leaves and branches.

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    Sparrow

    Any bird with a short, thick-based, conical bill spends a lot of its time cracking and eating seeds. Sparrows have moderately sized seed-eating bills.

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    Finches

    Finches have conical, seed-cracking bills of many sizes. Notice how this siskin’s bill is longer and more slender than the goldfinch’s behind it.

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    Grosbeak

    Grosbeaks have extremely heavy and powerful beaks that make short work of hard-shelled seeds. They are famous among bird banders for giving painful bites.

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    Crossbill

    Crossbills slip their curious-shaped bills into closed pine cones. As the bird opens its bill, the tips pry apart the cone’s scales, allowing the tongue to dart out and grab a seed.

Start with the bill – that all-purpose tool that functions as a bird's hands, pliers, knitting needles, knife-and-fork, and bullhorn. A flycatcher's broad, flat, bug-snatching bill looks very different from the thick, conical nut-smasher of a finch. Notice the slightly downcurved bills of the Northern Flickers in your backyard. That's an unusual shape for a woodpecker's bill, but perfect for a bird that digs into the ground after ants, as flickers often do.

Bills are an invaluable clue to identification – but tail shape and wing shape are important, too. Even subtle differences in head shape, neck length, and body shape can all yield useful insights if you study them carefully.

Noticing details like these can help you avoid classic identification mistakes. An Ovenbird is a common eastern warbler that has tricked many a bird watcher into thinking it's a thrush. The field marks are certainly thrush-like: warm brown above, strongly streaked below; even a crisp white eyering. But look at overall shape and size rather than field marks, and you'll see the body plan of a warbler: plump, compact body, short tail and wings, thin, pointed, insect-grabbing bill.

Measure the bird against itself

This is the most powerful way to use a bird's size for identification. It's hard to judge a lone bird's size, and an unusual posture can make shape hard to interpret. But you can always measure key body parts – wings, bill, tail, legs – against the bird itself.

  • Comparison of downy woodpecker and hairy woodpecker beaks

    Beak Size: Extra Large or Extra Small?

    Downy and Hairy woodpeckers have almost identical markings and occur in many of the same habitats. One of the best ways to tell them apart is to judge the length of the bill compared to the head. The Downy Woodpecker's is on the small side, measuring only about half the length of its head. The Hairy's is long and sturdy, about the same length as the head.

  • Comparison of hawks

    Head and Shoulders

    The two common accipiters of North America, Sharp-shinned and Cooper's hawks, are difficult to tell apart in the field. One useful trait is the size of the head compared with the rest of the body. The Sharp-shinned Hawk has a small head that barely protrudes ahead of the wings. The somewhat larger Cooper's Hawk has a much more prominent head.

Look for details like how long the bird’s bill is relative to the head – a great way to tell apart Downy and Hairy woodpeckers as well as Greater and Lesser yellowlegs, but useful with other confusing species, too. Judging how big the head is compared to the rest of the body helps with separating Cooper’s Hawks from Sharp-shinned Hawks in flight.

Get in the habit of using the bird itself as a ruler, and you’ll be amazed at how much information you can glean from each view. Good places to start include noting how long the legs are; how long the neck is; how far the tail extends past the body; and how far the primary feathers of the wing end along the tail (or past the tail).