Mystery Island

The new Mystery Island on Union Bay.

On Oct. 30th John McDermott sent me a video and a message asking if I knew anything about this new island. The island was a total surprise to me. During the past 15 winters, I have never seen an island appear at this location. Many small islands appear further to the north and I have usually associated them with the declining lake level during winter. However, this island is in the southern part of Union Bay, immediately north of the well-used boat channel, which connects Montlake Cut to Lake Washington. Based on multiple observations, John believes the island first appeared on October 30th or at most just a few days before.

The photo above was taken from the 520 Bike Path. It helps to show the location of the island however the distance involved minimizes the island's size. By pacing and counting along the 520 Bike Path, I concluded the island is probably around 100 yards long - east to west. This estimate includes the smaller unattached fragment to the west.

Here is another perspective. Last week my friend, Dave Galvin, and I visited the new island via kayaks. In this photo, Dave provides an eye-level perspective of the length of the island, when looking west. The bulk of the island is surprisingly flat and only a few inches above the water level.

There are somewhat taller lumps on the south side, closer to the boat channel.

The first theory I considered, regarding the island's origin, was that it appeared because the water level was unusually low. The depth of Union Bay, Lake Union, The Ship Canal and all of Lake Washington, has been managed at the Ballad Locks for over 100 years.

Click Here to read how the US Army Corp of Engineers (ACE) maintains the water level between 20' and 22' above sea level year-round. When you follow the link, if you scroll down you will see a graph that shows a set of historical averages for the water level. The trends on the graph show that in October the water is, typically, not yet at its lowest level and that it normally descends through November and by December it is usually at about 20', where it normally stays through mid-February.

The next question was, Has the water been lower than normal in the last month such that it would explain the island's unusual appearance?

(I was unable to link directly to this document at the ACE website so I copied it here instead.) 

This graph shows this year's October and November measurements, at the Ballards Locks are within the historical trend. The water level was higher on October 30th and then descends through November. This implies to me that the Union Bay water levels were not low enough to explain the island's sudden appearance at the end of October. 

This photo looks north. I am guessing the island is approximately 25 to 30 yards wide, i.e. north to south. This photo also shows an amazing abundance of shells. 

The day before Dave and I visited, I stopped at the small dock on the north side of Marsh Island. I wanted to see how birds were adapting to the new island. 

From the dock, I could see Marsha in her newly reconstructed nest just south of the Totem Pole, at the southeast corner of Montlake Cut.

Out on Mystery Island, Monty, her mate, was eating a fish while the American Crows harassed him, apparently hoping for leftovers.

While he was eating, three Trumpeter Swans flew in for a brief visit to the Bay. They did not stay long before turning around and leaving. They were last seen heading north along the eastern side of Webster Point. 

A male Belter Kingfisher flew back and forth on the north side of Marsh Island occasionally chattering quite loudly.

A pair of Buffleheads flew past but did not stop at the new island.

After Monty finished his fish, he returned to his favorite cottonwood tree just to the north of the Waterfront Activities Center (WAC), which helped confirm to me that he truly was Monty. 

Later, he flew out again, quickly grabbed a second fish and took it to a large horizontal branch in a cottonwood tree a bit further to the north.  Apparently, he wanted to eat it without harassment from the Crows. 

There have been American Crows on the new island every time I have checked. Initially, I assumed their primary reason for being there was because it provided a safe staging spot when they were coming and going from their nightly roost in Bothell.

However, once Dave and I reached the island, we noticed there was another reason they were there. They were picking through the clam shells looking for food. 

Occasionally, a Crow would pick up one of the shells, liftoff a few feet, and then drop it. The shells would simply "plop" onto the surface. There did not appear to be any chance the shells would break on impact. Dave mentioned he has seen Crows successfully use the same technique on city streets. Life is a learning process.

However, the island was just too soft and moist. I easily inserted my paddle into the "soil". Looking at the embedded vegetation Dave and I concluded it was probably peat. I began wondering, How soft is it?

When I tried placing a foot on the island, it immediately sank. That was before I even tried to transfer any weight onto it. I hesitated. Dave quickly convinced me that I would probably sink, up to my armpits, if I tried walking on the island. Given the cold and windy conditions, even with a life vest on, getting back into the kayak would have been problematic. I choose to stay in the kayak.

We explored a bit more but ultimately turned into the wind and paddled back to Duck Bay.

This week, the weather was better and the wind was calm. I came back to take longer look. 

I was able to sit for a while and observe the Crows more closely.

They were finding occupied shells on the ground...

 ...and prying out the meat.

When I arrived in the middle of the day, more than fifty American Crows were searching for food on the island. I am not at all surprised that Crows are smart enough to adapt to a new food source.

I am surprised that during multiple visits I have not seen any Killdeer or Wilson's Snipes looking for food on the new island. Especially, since they are regularly seen nearby on the small island just north of the Waterfront Activities Center.

When I left Mystery Island, just before dark, I counted over one hundred Crows. They do seem to also be using it as a nightly staging area.

All the clam shells, especially the full ones, imply to me that not too long ago this island was on the bottom of Union Bay. If the dropping water level does not fully explain the island's sudden appearance then, logically, the island must have risen to the surface. 

Dave Galvin asked David Williams about peat islands on Union Bay. David responded with the following information from a "Montlake Landfill Information Summary."

I searched along the edge of the island trying to find an angle where I could photograph and prove that Mystery Island was a floating mat, i.e. that it is unattached to the bottom of the bay. Everywhere I looked, the underwater edge of the island declined gradually, like a normal lake bottom. I cannot see any indication that the island is a floating mat. Plus, it does not seem to be moving at all. 

Even now, the water level is near the usual annual low but not at its all-time low. Plus, I can personally remember seeing lower water levels and more exposed shore around Union Bay in previous years. But in the last 15 year I don't ever remember seeing this island.

Note: Click Here to see a WSDOT photo from January 2024. There is no indication of the new island in the photo and yet the water level was most likely lower in January than it was on October 30th, when the island was first noticed.

On the other hand, this 1951 map, found inside the original cover of the book "Union Bay" by Higman and Larrison, does show a smaller island in nearly the same place. 

Since then, dredging occurred to support the first 520 bridge construction, at which time Marsh Island was most likely created, then in the last decade the first 520 bridge was removed and the new one built. Plus, there has been ongoing wave action from the boat traffic in the channel, for over one hundred years, plus I suspect some dredging of the boat channel. All of this activity could easily have stirred up and detached peat from the bottom of the bay. 

Still, I remain mystified. If this island is floating peat, why does it appear to be a stationary, as if it is simply exposed lake bottom? If it is not floating and until lately, really was the bottom of the Bay, Why was it exposed when the water was not at it lowest level, annually or historically? 

Could it have floated to the surface, then blew over and got stuck in the shallow area where it currently resides? If so, Why don't we see any unsupported mats of peat breaking off and floating away? 

If you decide to check Mystery island out for yourself, the easiest approach is via Marsh or Foster Islands. However I would suggest bringing your binoculars. Together, we can take turns watching to see when (or if) the island floats away or disappears below the surface. Plus, we can also watch for any new bird species on the island. So far, I have seen the American Crows, one Bald Eagle, a dozen or so Canada Geese and two Mallards on the island.

Have a great day on Union Bay...where nature lives in the city and Black Birders are welcome!

Larry

Going Native:

Each of us, who breathes the air, drinks water, and eats food should be helping to protect our environment. Local efforts are most effective and sustainable. Native plants and trees encourage the largest diversity of lifeforms because of their long intertwined history with our local environment and the local native creatures. Even the microbes in the soil are native to each local landscape. 

I hope we can inspire ourselves, our neighbors, and local businesses to respect native flora and support native wildlife at every opportunity. I have learned that our most logical approach to native trees and plants (in order of priority) should be to:

1) Learn and leave established native flora undisturbed.

2) Remove invasive species and then wait to see if native plants begin to grow without assistance. (When native plants start on their own, then these plants or trees are likely the most appropriate flora for the habitat.)

3) Scatter seeds from nearby native plants in a similar habitat.

4) If you feel you must add a new plant then select a native plant while considering how the plant fits with the specific habitat and understanding the plant's logical place in the normal succession of native plants. 

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Keystone native plants are an important new idea. Douglas Tallamy, in the book "Nature's Best Hope ", explains that caterpillars supply more energy to birds, particularly young birds in their nests, than any other plant eater. He also mentions that 14% of our native plants, i.e. Keystone Plants, provide food for 90% of our caterpillars. This unique subset of native plants and trees enables critical moths, butterflies, and caterpillars that in turn provide food for the great majority of birds, especially during the breeding season. 

Note: Flowering plants and trees, i.e. those pollinated by bees, are also included as Keystone Plants.

This video explains the native keystone plants very nicely:

https://www.youtube.com/watch?v=O5cXccWx030

The Top Keystone Genera in our ecoregion i.e. Plants and trees you might want in your yard: 

Click Here

Additional content available here:

https://wos.org/wos-wp/wp-content/uploads/2022/10/Native-Plant-Resources-10-7-22.pdf

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In the area below, I am displaying at least one photo with each post to help challenge us to know the difference between native and non-native lifeforms. 

Fall is a great time to plant trees because they need less care over the winter and are more likely to survive and thrive come spring. The most beneficial trees (for bird, insects and the ecosystem) are native trees. 

Is this a native or non-native plant? How about the fern?

Scroll down for the answer.

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Spurge Laurel: This plant is a toxic non-native weed. The sap, fruit and leaves can cause skin irritation. Gloves and other protection are recommended when removing it. In drier habitats, i.e. around Garry Oaks and on the San Juan Islands, it can be especially troublesome. In some places it is recommended to remove it, bag it, and trash it. Apparently, putting it in the "Clean and Green" may actually enable it to spread further in the future. (The fern is a native Sword Fern.)

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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. As of 2021, Google has discontinued the service.

In response, I have set up my own email list. With each post, I will manually send out an announcement. If you would like to be added to my personal email list please send me an email requesting to be added. Something like:

                Larry, Please add me to your personal email list. 

My email address is:  

                     LDHubbell@comcast.net

Thank you!

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The Comment Challenge:

Another common issue is losing your input while attempting to leave a comment on this blog. Often everything functions fine, however, sometimes people are unable to make it past the robot-detection challenge or maybe it is the lack of a Google account. I am uncertain about the precise issue. Sadly, a person can lose their comment with no recovery recourse. 
Bottom Line: 
If you write a long comment, please, copy it before hitting enter. Then, if the comment function fails to record your information, you can send the comment directly to me using email.

My email address is:  

                     LDHubbell@comcast.net

Sincerely,

Larry

Final Photos, etc.: