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It’s a mixed bag out there.  You’ve got your yard set up to attract birds – feeders, baths, maybe some native plants and brushpiles.   But as with any open house buffet, you’re likely to get a few guests who don’t behave as well as you’d like.

Adult Cooper's Hawk (Accipiter cooperii)

At best, the others don’t want to hang out with them.   Sometimes they get violent, and occasionally kill and eat the other guests...  really does dampen the mood, ya know?  

This is a repeat of a diary first published as "Backyard Bad Boys" in October '07 and updated a bit in 2010.  Because we'll be on a field trip today, I'm not going to be able to tend this diary properly, which is why you're getting a rerun.

But this is one of those areas of identification that causes a lot of confusion for people, and there's a lot of useful info herein.  I've even added a bit of new stuff on two other confusion species.

So who are they?  Well, almost any raptor could turn up in your backyard, depending on where you live.  I’ll stick to three of the most common:  Cooper’s Hawk, Sharp-shinned Hawk and Merlin.  (Another common back yard predator in many areas is the American Kestrel;  some fellow Kossacks have done their part to help familiarize you with these fine little falcons.)

Since most of my non-birding friends know that I work with hawks, they come to me when they want to identify one that they've seen.  Unfortunately, most of the hawks are described thusly:  "Well, it was brown and kinda streaky..."  That description covers about 90% of the juvenile hawks out there, and about 98% of the juvenile hawks that you're likely to see in your neighborhood.  So let's go beyond "brown and streaky".

Sharp-shinned and Cooper's Hawks are accipiters, aka “true hawks”.  (There is one other member of their family in North America, the Northern Goshawk.  If you have Goshawks as yardbirds, I’m not sure I want to hear about it... unless you have photos to share.)  They have evolved to hunt birds on the wing, and are built for maneuverability in brush and woodlands.   Accipiters have short, round wings and long tails which serve as a rudder of sorts.  In your yard, they’ll hang out in a tree or a bush, then burst out to surprise the birds at the feeder, trying to grab them on a short flight.  

A trio of Sharp-shinned hawks, showing accipiter shape:  short round wings, long tails.  These are all adults; notice that the females are browner than the males - don't let that confuse you into thinking they're juveniles.  More below.

Compare that shape with the buteos – the soaring hawks – who have long, broad wings and short, broad tails, which helps them work updrafts and thermals with maximum efficiency.  

If you see an perched hawk, one of the first steps in identifying it is to check the wing-to-tail ratio if you can see it.  On accipiters, the tail only comes about halfway (or less) down the tail; on most other hawks and falcons the wings are nearly the same length as the tail.

Sharpie and merlin – note difference in wing/tail ratio.

Of the three, Cooper’s Hawk, Accipiter cooperii, is most likely to be seen year round (at least in my part of the country).   Sharpies breed further north and at higher elevations; Merlins are mostly tundra breeders.  Coops have adapted to humans pretty well; they often breed in suburban neighborhoods with mature trees, as well as in the countryside.  They are the largest of the three birds discussed here, roughly crow-size.   Juvenile birds are brown and streaky on the front, brown with rufous (rusty) scallops on the back and have yellow eyes.  Adults have rufous barred fronts and grey backs – warm grey on the females and slate grey on the males.  Their eyes range from pumpkin to deep garnet red, deepening in color as they age.  Adults and juvenile share some characteristics; they have noticeably rounded tails, and often have a “block-headed” appearance.

Cooper’s Hawks, showing that “blockhead” look – brown and streaky juveniles, and a rufous-and-grey adult.

Coops were hunted as barnyard pests for decades.  They are the original “chicken hawk” – so called because they couldn’t resist feasting on the easy, slow-moving, tasty prey available on most farms.  (Unlike modern limbaughian chicken hawks, Cooper’s Hawks have actually faced gunfire.)   Distressing as it may be to us to watch one pick off a robin at the feeder, at least it’s less likely to get them killed by humans.  They will take birds as small as warblers and finches, but generally go for larger prey like robins, starlings, jays, flickers and quail.  Females can easily take prey as large as pigeons.

Sharpie back view: brown w/rufous scallops on juvs, grey on adults (slate grey on males)

Sharp-shinned Hawks, Accipiter striatus, are one of the smallest North American raptors; they’re roughly jay size.  They generally take smaller birds like warblers, finches and chickadees, but females can take some larger prey.  They are very similar to Cooper’s Hawks in appearance – brown and streaky juveniles, grey backed/rufous fronted adults.  Some juvenile sharpies have a lot of rufous tones on the breast, so it helps to see the back to age them properly.  Tails are more squared off, compared to the coops.  Eye colors are the same as coops – yellow on the juveniles, gradually changing from golden orange to deep red in adults.

Sharpies, showing that “bug-eyed” look – yellow eyes on juvs, orange to red on adults.

Even very experienced hawkwatchers can have difficulty telling the two species apart.  It’s more difficult in the west because our coops are much smaller than the eastern birds, and male coops/female sharpies are very close in size.  If you can get a good look at them, there are few ways to tell them apart.   On perched birds:  First is the tail shape, as mentioned above – coops are more rounded overall and sharpies are more squared off – and to me, it’s the individual feather shape as well as the tail shape.  (an easy mnemonic – coops are rounded, like all of the letters in their name; sharpies have sharp corners)  Second, look at the legs/feet.  Coops have pencil-thickness legs, with fleshy toes.  Sharpies have sharp shins – little toothpick legs – and spidery, skinny toes.   Getting more subjectives, coops have blocky, wedge shaped heads with heavily browed eyes.  Sharpies have rounder heads, and they often have a bug-eyed look – in profile, sharpie eyes seem “mid-head” while coops are closer to the front of the head.

Sharpie on left, dark-eyed Sharpie (aka Merlin) on right

So, your bird is small and brown and streaky, like a sharpie.  But its eyes aren’t yellow, they’re dark.  Take a look at those wings again... oh, nearly as long as the tail.  You’ve got a Merlin, Falco columbarius, in your yard.   Like most falcons, merlins are bird-eaters, and they’re built for overtaking their prey through speedy flight.  The accipiters in your yard will grab their prey and squeeze it with their feet; the falcons use their specially adapted beak to sever the neck and dispatch their victim instantly.  

Merlin, showing the narrow, tapered wing typical of falcons (compare to accipiters), long tail – but wingtips come much closer to tail length.

These small falcons often prey on shorebirds and can often be found on coastal mudflats.  Most of them breed in the tundra and only get to the lower 48 in the winter.  (Merlins are a circumpolar species and can also be found in Eurasia.)   In addition to shorebirds, they eat many small passerines, and have learned to make the most of backyard bird feeding stations.  Merlins have one other notable prey item – they really go for dragonflies, and their migration often tracks dragonfly migration closely.  It’s quite entertaining to watch them grab one and eat it in the air.

One thing that led me to lump these three together as backyard predators – they share an unfortunate tendency to die by smacking window when chasing birds near feeders (the little birds usually die, too).  To the extent that you’re able to position your feeders and baths away from picture windows, you’ll make your yard safer.

Two other species that should come into this conversation:  Red-shouldered Hawks (yea for lineatus!!) and Peregrine falcons.  For both of these species, it's the brown and streaky juveniles who can cause confusion - the adults are pretty much unmistakable.

If your "Cooper's Hawk" looks kinda chunky and has dark eyes, then it's not a Cooper's Hawk.  In all likelihood, it's a juvenile red-shoulder.  Look at the eye color first, and then notice the bolder patterning.  Although all of these hawks have stripes in their wings and tails, most of them have a light/dark brown stripes - on a red-shoulder, it's more black and white, leading to a checkered appearance on wings and tails.

(Yes, I found yet another excuse to post a picture of a 'shoulder...)

And peregrines.... sigh.

If you live in a highrise apartment building, or at a beach house with nearby mudflats, or near mountains/canyons with sheer cliffs - your backyard bird could be a peregrine.  But if you live in a more typical residential area, with trees and maybe some forests... not so much.  And if the bird is sitting in your trees and bursting out after the birds at your feeders, it's not a peregrine.  I know it looks like the bird in the picture, but look at the eye again.  Really.  The great thing about nest cams is that they've introduced a lot of people to these amazing raptors; the bad thing about nest cams is that they don't show much else about how the birds live.  So many people over the years have told me about the peregrines in their back yard and I hate to have to break it to them that it's remarkably unlikely.  Peregrines hunt from on high, or in wide open spaces.  They're just not built for backyard hunting.  (On the outside chance that it is a real, honest-to-god, dark-eyed, long-winged peregrine in your yard, keep an eye on it because it may be in trouble.)

I wrote another diary about raptor ID in 2012 that expands on some of this a bit.  It was supposed to get a Part 2, but I never had time.  Well, maybe that will be my next diary...

Originally posted to lineatus on Sun Jan 26, 2014 at 06:00 AM PST.

Also republished by Birds and Birdwatching.

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