ntifying Coopers and Sharp-shinned hawks in your yard

BIRD COLUMN FOR JANUARY 23, 2005

By Benjamin P. Burtt

TOPIC: Identifying Coopers and Sharp-shinned hawks in your yard.
Announcement: The February Feeder Survey starts Sunday February 6

INTRODUCTION
This column contains all of the material that appeared in the Bird Column in the Post Standard in Syracuse on the above date.

However, this web version contains additional information and additional photographs for the reader who is interested in learning more about how to identify individual birds of these very similar species.

Dear Mr. Burtt:
I am sending you a picture I took of a hawk in my backyard on October 24. We think it is a Coopers or a sharp-shinned hawk. It seemed to be bigger than a crow. Can you help us identify it?
-Mike Reissig, Liverpool.

Figure 1 Courtesy of Mike Reissig

Dear Mike:
You are correct that the bird is either a Coopers or a sharp-shinned hawk. The markings on your bird will fit either species. We can also say that it is an adult bird as will be clear in the discussion below.

So how can we determine which species it is?

These hawks belong to the Accipiter Family that are referred to as the Bird Hawks because they feed mostly on birds. There is a third member of the family, the Northern Goshawk which is larger and the adult has a somewhat different appearance. In identifying the Coopers and sharp-shin we will use the way the birds are marked, the size, the shape of the bird and the shape of the end of the tail. Lets take those up in turn.

SIZE

The painting in Figure 2 below shows the adults of both species. Note that the sharp-shinned hawk is smaller on the average than is the Coopers. Unfortunately, when we see a bird alone, it is difficult to tell how big it is. We need to compare its size to the size of another bird that we know. If you would measure the piece of drift wood the bird is perched on in your photograph, we can compare the size of the bird in the picture to the piece of wood and make that comparison.

Figure 2 Courtesy of Julie Zickefoose:

A sharp-shinned hawk is shown on the left. The Coopers hawk is on the right. Note the squared off end of the sharpie’s tail and the rounded end of the Coopers. The horizontal lines on the breast show that these are adults. Immature birds have brownish lines running up and down. This painting by Julie Zickefoose is from the forthcoming book, “Identify Yourself: The Top Birding Identification Challenges” by Bill Thompson, Editor of Bird Watchers Digest

Here are some measurements that would help us use size to identify the hawks. If you measure the distance from the tip of the beak to the tip of the tail of sharp-shins, the specimens range from 10 to 14 inches. The same measurements on a Coopers hawk are 14 to 20 inches. So their sizes overlap.

Complicating the use of size is that among hawks and owls, the female is larger than the male. A female sharp-shinned hawk can be the same size as a male Coopers hawk.

If you could measure the bird and the length is clearly less than 14 inches it is a sharp-shin and if it is greater than 14 it is a Coopers. If it was just 14 inches you could not be sure based on size alone.

In your message you said that the bird was about the size of a crow or even larger. Since the crow can be 17 to 20 inches, that would tend to rule out a sharp-shin.

The shape of the bird

The Coopers has a slightly larger head in proportion to its body and a somewhat longer neck. These are hard to judge for the bird can stretch its head up or “hunch” down a bit. On the basis of the body shape I tend to think it is a Coopers.

The tail

The best “field mark” when the birds are perched, as in the painting, is the shape of the end of the tail. Note that it is rounded on the Coopers and straight across on the sharp-shinned.

You can see this if the bird is relaxed and the tail feathers are not fanned out. Unfortunately, in the photograph you sent, the tip of the tail is concealed by a branch.

The plumage of adults and juveniles

The birds shown in Figure 2 above, are adults. They have the rusty barring ( horizontal lines) across the chest. The back and wings are a bluish gray.

Now, lets now look at Figure 3 , here are the immature birds also painted by Julie Zickafoose. This is how they look during their first year. The wings and back are brown and these birds have a streaked breast, that is the lines run up and down.

Figure 3 Courtesy of Julie Zickefoose

It is common usage in field guides when describing lines on a birds breast to use the word “barring” when the lines run left and right and to use “streaks” when the lines run up and down. ( My dictionary does not mention this use of the words. Streaks and bars seam to mean much the same thing in it.)

From the general body shape, the breast markings and your estimate of size, I would vote for an adult Coopers hawk. If we could see that the end of the tail is rounded, we would be certain.

During their second year the Accipiters look much like the adults, but it may take an additional year before they get the full adult plumage.

Another Hawk Identification Question

Here is a photograph taken by Carolyn Pyle of Freeville. Jim and Carolyn asked if I could help them identify the bird.

Figure 4 Courtesy of Carolyn Pyle

This photograph taken from the rear shows a brown back. In this case we know exactly how big the bird is. In discussing the bird over the telephone, I asked whether the bird was actually perching on that wire fence. Assuring me that it was indeed perched there, the next question was, what are the dimensions of the openings in the mesh? It had a mesh 2 inches wide and 4 inches high. The bird from top to bottom therefore is about three mesh openings high, or about 12 inches.

That makes it too small to be a Coopers hawk, but is quite correct for the sharp-shinned hawk. The brown color suggests a first year bird. But what are those white spots on the wings?

I have not seen very many sharp-shinned hawks in the wild so telephoned Dr. Kevin McGowan of the Cornell Laboratory of Ornithology. When I described it to him he said that such spotting on the wings is common on the immature birds. Later the Pyles sent him a copy of the photo and he confirmed its identity as an immature sharp-shinned hawk.

After all this, I searched my field guides for a picture of the back of a juvenile sharp-shin. I finally found a photograph in Kenn Kaufman’s “Birds of North America” on page 117. It is almost a duplicate of Carolyn Pyles photograph. There was no image in Peterson’s latest Field Guide nor in The Sibley Guide to Birds or the Stokes Guide.

So, when you see a hawk looking over the birds in your yard, it will probably be a sharp-shinned or Coopers hawk. It appears there because it is hungry too. You may have mixed feelings about it feeding on one of “your” chickadees, but it gives you an opportunity to see a relatively rare bird in your yard.

Protecting your feeder from hawks

You may wish to minimize the number of your birds that the hawk captures. First, it is wise to have shelter nearby. This can be a hiding place, such as a dense evergreen or a big brush pile within 6 to 10 feet of the feeders.

Since it is the activity of many birds near your feeder that gets the hawks attention, you can stop feeding birds for 3 or 4 days. After the hawk has gone elsewhere, put out the food again and the hawk will probably have found another place to hunt.