Mission: To promote the appreciation of wildlife and increase harmony between humanity and nature.

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Saturday, March 21, 2015

Investment Versus Expense

This male cooper's hawk is looking into the future and making some tough choices. 

Not only must he select... 

 …just the right branches but… 

...he may also be wondering whether his nest building efforts are an investment or an expense. 

Those of us who are not accountants might legitimately ask, What's the difference?

Here is the first example that came to mind. When I was young my uncle introduced me to his grandfather, who had sold sewing machines to farming families, in the early part of the 20th century. Sewing machines were new and expensive, but the farming families could easily justify the investment. A machine would pay for itself, by saving time that would otherwise be spent sewing clothes by hand. 

When the traveling salesman bought his inventory, the sewing machines were an investment. The machines would eventually sell for more than the initial cost. The cost of feed for the traveling salesman's horse, which pulled the wagon that carried the sewing machines, was an expense. The feed did not increase in value, it was just a cost of doing business.

Male cooper's hawks often create more than one nest. Sometimes the extra nests are not even used. It makes one wonder why the hawks go to all the effort. Maybe they create the extra nests as a secondary option in case predators discover the first nest or the first nest is blown out of the tree. Maybe the extra nests are decoys to distract predators. Another possibility is, that an extra nest shows that the male has the energy and skill to provide for a growing family e.g. to attract a mate. A nest used to raise young is an investment, but the extra nests seem a bit more questionable. What do you think? Are they an investment or an expense?

By the way, the long feathers in the photo above are tail feathers, not wing feathers. 

Relative to other birds, the cooper's hawk has a very long tail that helps it maneuver between branches with ease. Here the male jumps off the nest, heading out to secure more branches, without even opening his wings. He uses his tail like a rudder to guide his body through the tangle of maple branches. The male always searches for small dry branches high in the trees. He never exposes himself to the risks, like off-leash dogs, that would come from picking up branches off the ground.

 While the male works at building the nest, a young female observes the process.

She constantly shifts position to keep the male in view while he flies back and forth between the nesting tree and nearby douglas firs or western red cedars. The coniferous trees seem to have much more brittle branches that are more easily removed from the trees. While watching the birds a piece of broken branch landed on my head and stuck in my hair.

The youth of the female is evident from the dark, vertical, teardrop-like, stripes on her chest. This indicates she hatched out last year and is in her second calendar year. Even though she is young, she is old enough to take a mate.

The more mature male has orange irises, instead of yellow, and reddish-orange horizontal bars on its chest. 

In this photo you can see that the male is wearing jewelry, e.g. bands around his legs. The female has not yet been banded.

Ed Deal has been banding cooper's hawks and peregrine falcons, in our area, for a number of years. The goal is to learn more about the birds and help them to thrive. Historically, cooper's hawks were shy and choose to stay away from cities. The last couple of years the number of cooper's hawks in Seattle appears to be growing. It seems like most parks, and even just neighborhoods with large trees, have cooper's hawks. 

(Just like barred owls, cooper's hawks also catch rats. Studies show that rat poison does bio-accumulate in birds and kill them. Rat traps are just as effective and much less dangerous to birds, pets and the environment.)

The key to tracking and learning more about the birds is the bands. Ed applies purple bands to the left leg of male birds. Orange bands are applied to the right leg of females. Both genders have metallic bands applied to their opposite leg.

There are unique codes printed on the colored bands. In this case the male has the code "3 over 3" on his purple band. This band was applied by Ed's colleague, Martin Muller, during the bird's first summer in July 2013. According to Ed's records, this bird was spotted again in August 2013 and then in October 2014.

If you would like to help track cooper's hawks you will need a pair of binoculars and a willingness to get a stiff neck while searching the tree tops. It also helps to listen for their calls. Ed sent the following set of links to help identify the calls of cooper's hawks.

An adult female: http://ibc.lynxeds.com/video/cooper039s-hawk-accipiter-cooperii/two-frontal-views-adult-perched-looking-around-calling-soft  A female will also make the "kekking" sound, like the males.

After you follow this link click on either "Food delivery to nest" or "Begging calls of chicks"

Now is an especially good time to watch for cooper's hawks because our big-leafed maple trees have not yet leafed out. If you spot a male bringing branches to a tree, I would be happy to pass new locations on to Ed, so he and his team are aware of the potential nesting sites. (My email is: ldhubbell at comcast dot net.)

All About Birds says, a study of cooper's hawk skeletons showed... 23 percent had healed over fractures to there chests. (Look under Cool Facts.) 

If you watch the way they fly between branches and around trees you will understand why.

The other day, while photographing a woodpecker, two birds flew past me very quickly.

They were way too fast for me to identify, but the first bird sounded like a very anxious robin.

They wove between the trees, with the second bird immediately behind the first. Given that we were not far from this nest, plus the speed and the close pursuit, I suspect the robin was fleeing from one of the cooper's hawks. They passed within 2 or 3 feet of me before disappearing into the underbrush. It made the hairs on my neck stand up. It also made me happy to be bigger than a cooper's hawk.

While writing, I just watched a crow breaking a branches off our neighbor's tree and flying away with them. Spring is here. Nest building is under way. We are beginning the most exciting time of the year! Hopefully, all the nests being built are wise investments, that pay high dividends.

Have a great day near Union Bay…where cooper's hawks nest in the city! 



By the way the PNW Nature Blog Scavenger Hunt that started last week has been extended through Sunday night. Last I heard, some of the prizes may still be available.

The goal is to answer a nature question on each of a variety of PNW nature blogs, just one question per blog.

The Union Bay Watch question is, "What treasure is scheduled to be hidden next to the ponds at the Union Bay Natural Area?" You will need to read last week's post to find the answer. You can scroll down or click the following link.

To learn the rest of the questions and the other nature blog locations please visit:



  1. Thank you for another winning show! I appreciate your comment about rat poison. What about weed killers that some neighbors use on their yards?

    1. Anita, You are welcome! I do not know of a direct connection between the weed killer and the birds, but it certainly washes into our rivers and streams pollutes the fish and bio-accumulates in the salmon and orcas, with a negative impact. I have not seen any studies yet, but I suspect it could indirectly impact many fish eating birds as well. We should think of "weeds" as a sign of a healthy environment and a safe place for children to play.
      Thank you for the reminder.:-)

  2. Love the Coop!

    Dianna Moore

  3. Dianna,
    Thank you for the kind words and the link. Since the WHO finds it as a probable carcinogen, I will not be spraying it around my house, near my family and adding it to the environment.
    Thanks again.