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

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Sunday, December 10, 2017

A Pirate's Bounty

Our local bald eagles enjoy sitting in the tree tops just north of the Waterfront Activity Center (WAC). They spend hours gazing out across Union Bay.

On Friday, two different people asked me if the eagles were nesting near the WAC. I think the question is a good one. It most likely indicates that the eagles are being seen consistently in the area. It might even imply that the observer has noticed that the eagles are mature birds, sitting side-by-side and apparently a mated pair. (The fully white heads and tails only appear when bald eagles are mature enough to take a mate, build a nest and raise young.) Actually, seeing a mated pair consistently in the same area probably does indicate that the eagles are nesting nearby. The question is, What is your definition of nearby?


Of course, mature eagles are not the only ones that can be seen near the WAC. Friday afternoon, I spotted this third-year bird hiding among the cottonwood branches. Click Here if you would like to learn more about estimating the age of an eagle.

However, four fully mature bald eagles often hang out near the WAC. This photo shows the northern pair which prefer this deciduous tree. The southern pair (in the first photo) are consistently found in the same coniferous tree between the dock and the WAC parking lot.

In August, I watched the northern pair get excited and start calling. Surprisingly, I have even watched them call out to the southern pair of eagles when they come in off the bay. I have saw no signs of malice between the two pairs. Their calls did not sound defensive or argumentative. They actually sounded like greetings.

Occasionally, one of the mature eagles will do a solo flight.

When a eagle glides over the bay the coots and wigeons scatter and fly. The smaller birds appear to open a path across the water in front of the eagle. It reminds me of a servant rolling out a red carpet for royalty. In reality, this behavior appears to be motivated by self-preservation and a grudging respect for sharp talons.

If one mate is already at the WAC they almost always call out a greeting. I find their melodic calls sound to like a slightly syncopated descending melody to me. If I wrote music to accompany cartoons, an eagle's call would fit nicely with a happy-go-lucky buffoon tumbling down a hillside. If you would like to form your own opinion regarding the musical skills of bald eagles, Click Here, and then scroll down.

Still, it is most common to see them visiting the WAC as a pair.

They can sit surprisingly close, especially given the size and sharpness of their talons.

Occasionally, they give each other a little breathing room.

Since they mate for life, which can extend over decades, they appear to develop a very strong bond. I wonder if we will ever find a scientific way to determine whether mated eagles feel something similar to what we call love. 

Both pairs of bald eagles nest next to Union Bay. Neither nest is visible from the WAC. However, from the eagles' perspective their respective nests are just a short flight away.

The southern pair (Eva and Albert) raise their young above the Broadmoor Golf Course - in this rather extensive nest. From what I have seen, most eagle's nests are made primarily of cottonwood branches. I suspect this nest may exceed two thousand pounds in weight. To give you an idea of the size, remember that the wingspan of a bald eagle is approximately six feet. I suspect the average human could sit and probably even lay down inside this nest. Although, I suspect the olfactory sensation might be less than desired - eagles love fish.

The nest of the northern pair is in a cottonwood tree on the north side of Union Bay. I find this nest difficult to view in the winter and virtually impossible to see when it is active - due to the profusion of cottonwood leaves come Spring.

Since the eagles do not nest in the immediate vicinity of the WAC you may be wondering what are they doing there?

Historically, I always thought the eagles were watching the coots, wigeons and other ducks. I suspected they were looking for careless waterfowl to consume. I imagined ducks so focused on securing their own food, that they allowed the eagles to occasionally swoop down and grab lunch. Over time, I have come to the conclusion that the bald eagles may be even more interested in the double-crested cormorants. With a dozen buoys in the water in front of the WAC, and a cormorant on nearly everyone, the eagles have plenty to watch.

Sometimes the buoys won't even hold all the cormorants. I admit that the cormorants are fairly large, cantankerous birds and I have never seen an eagle catch or eat one. I suspect the relationship between to species is slightly more complex. The eagles love fish and the cormorants are the best fishers on Union Bay.

Readers who have been following my blog for a while might ask, What about the osprey? Our local osprey are incredibly effective at catching fish, but I believe if you calculated the time spent per pound of fish caught the cormorants would win. They are a dark bird that dives down to the bottom and goes after the fish in its own element. They do not have to wait for a fish to wander close to the surface, as the osprey must.

Surprisingly, I believe the eagles are less effective at fishing than both the osprey and the cormorants. None the less, I think the eagles secure fish with less effort than either of the other two species.  

A few years ago I watched a bald eagle fly over my head, circle low just above the empty bay and then settle down into the water.

The actions were similar to what we see in this photo. After a moment, a cormorant broke the surface, just behind the eagle and flew away. The eagle slowly shook off the water and pulled itself back into the air. Eagles do not dive and are unable to reach down to where the bottom fish live, but when the eagle flew away it was carrying a large bottom fish - with obvious whiskers for feeling around in the muck. I believe, that as the cormorant approached the surface it was essentially given a choice. With an eagle waiting over head the question was, 'Your fish or your life?' At which point the cormorant choose life. 

Multiple times I have found the meatless remains of large bottom fish under the trees, where the eagles sit, next to the WAC. Given that there are plenty of fish and dozens of highly skilled cormorants on Union Bay the tax rate for each individual cormorant does not appear to be too burdensome.

Now that the football season is nearly over, and the Husky fans will no longer be visiting by boat, the buoys will be removed. This will lowered the number of perches for the cormorants, which may in turn lower the number of opportunities for the bald eagles to steal fish. I wonder if we will begin seeing less of the bald eagles in the immediate vicinity of the WAC.

Last week, I watched a third year eagle (which looked a lot like the bird I saw yesterday at the WAC) devour a fish at the Union Bay Natural Area. It makes me wonder at what age eagles learn to become pirates or is it simply in their genes. I have no doubt that bald eagles occasionally catch their own food - I have seen it happen. However, given the proximity to the cormorants and the amount of time our local eagles spend at the WAC I suspect that, at least during football season, their pirate's bounty is a major portion of their diet.

Have a great day on Union Bay...where nature lives in the city!

Larry


On Harmony:

I believe learning to live in harmony with nature requires that we pay close attention to the unintended consequences of our actions. Actions as different as putting out buoys during football season and driving to work in the morning. This article (Click Here to Read) mentions the toxicity of the runoff from the old 520 bridge, as related to coho salmon. The good news is that the new 520 bridge no longer allows runoff to fall into Lake Washington. I am hoping that we, and the bald eagles, cormorants and osprey, will begin to notice coho in Union Bay in the coming years.


Going Native:

Without a well-funded Environmental Protection Agency, it falls to each of us to be ever more vigilant in protecting our local environments. Native plants and trees encourage the largest diversity of lifeforms because of their long intertwined history with local, native creatures. I have been told that even the microbes in the soil are native to each local landscape. My hope is that we can inspire ourselves, our neighbors and local businesses to plant native flora and to support native wildlife at every opportunity. My intention is to include at least one photo each week and visually challenge us to know the difference between native and non-native lifeforms. Can you identify these trees?  Are they native to Union Bay?

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Scroll down for the answers


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A. I am fairly confident that this tree is an old world cedar tree and it is not native to Union Bay. There are three different trees that it might be. They are:

- Cedar of Lebanon
- Atlas (from Morocco and Algeria)
- Deodar (from the Himalayans)

I do not think the tree has the shape of a Cedar of Lebanon. In addition I believe most of the Atlas trees in Seattle are probably of the blue-green variety. So, I am guessing, but I suspect this is a Deodar cedar.




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The Email Challenge:

Over the years I have had many readers tell me that Google is no longer sending them email announcements regarding my posts. Even more frustrating when they go to 're-sign-up', hoping that will enable them to once again start receiving the announcements, they get a message which says 'Sorry, you are already signed up.' Google has not responded to my requests for help with this issue. 

My functional work around is to setup my own email list and each week I manually send out a new post announcement. If you are experiencing the issue and would like to be added to my personal email list please send me an email requesting to be added. Thank you for your patience!

My email address is LDHubbell@comcast.net



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2 comments:

  1. Regarding your observation of the two pairs of eagles greeting one another: On December 5, we saw one pair in what looks like a cottonwood between the dock and the WAC parking lot, singing to each other. Then another pair showed up, also singing, and the four of them did a little dance over the bay before one pair returned to the cottonwood and the other sounded like they'd settled down farther south. The food is so abundant that they amicably share it? Is somebody related to somebody?

    As to whether eagles may feel love: in view of my photo of two western gulls (which also mate for life) cuddling, I wouldn't be surprised. https://www.flickr.com/photos/35195017@N06/5983129786/in/album-72157627310710902/.

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    1. Beautiful and inspiring gull photos! Thank you for sharing, Dennis. So much to see and learn (and save) - we are very lucky to live when and where we do!

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