Tuesday, July 30, 2024

Tree Hawks

This adult Cooper's Hawk was seen circling above Montlake Cut in March of last year. It may seem strange to think of a bird in an empty sky as a "tree hawk" but even when soaring high overhead the shape of its body provides clues about its capabilities. 

For example, their fairly small size and relatively short rounded wings enable them to fly between tree trunks and branches that larger birds, like Red-tailed Hawks and Common Ravens, find challenging to navigate. (Cooper's Hawks are similar in size to American Crows.) Their long tails enable them to twist and turn quickly, which helps them follow small prey through dense foliage and underbrush. 

Not only do Cooper's Hawks often hunt in wooded areas locally they generally mate, build nests, hatch their eggs and raise their young in and among trees. The Arboretum is a perfect example. However, Cooper's Hawks are not all precisely the same. Individuals and their choices vary. For example, Cooper's Hawks nest in all 48 of the lower continental United States. I am sure that they must somehow survive in places where trees are scarce. Still, they do seem most perfectly adapted for life among trees.

For the last month, friends and I, have been seeing young Cooper's Hawks in the Arboretum. Many questions come to mind, How many are there? Where did they nest? Will the parents nest here next year? When folks see a young hawk laying on a limb, like the one in this photo,  they ask, What is it doing? Is that normal?

I don't remember ever seeing a mature Cooper's Hawk belly-down in the middle of a branch. 

I suspect among the young ones this is a carryover habit from spending time lying down in the nest. By Fall, when they are out hunting on their own, and their parental food supply has been terminated, I expect this habit will be forgotten. Among adults, I only remember seeing them in a somewhat similar horizontal position during mating and brooding.

By the way, the white spots on the back of a Cooper's Hawk are one of the indications of youth. The spots imply it either hatched this year or at most last year. My friend Martin, from Urban Raptor Conservancy, says that by the end of August, during their second year, the spots are typically gone.

Here is an example of an adult Cooper's Hawk with a relatively spotless back.

Vertical dark brown spots on the chest are another indication of youth. 
(Note: This is the same bird that you will see later with ruffled feathers.)

Among adult Cooper's Hawks, their chests have a horizontal orange barring. Their eyes seem to transition over time. The more mature birds seem to have vibrant orange irises that sometimes even deepen into a stunning red.

Among the youngest, i.e. a few months old, the eyes often reflect a sky-blue color. However, sometimes, I wonder if I am seeing a very pale green or yellow reflection instead.

Later, as they approach maturity and for a while thereafter their irises appear to go through a brighter yellow stage. This particular young one was spotted in early Spring among some trees next to Useless Bay on Whidbey Island. (The March wind, blowing in off the Sound, provided a perfect example of having one's feathers ruffled.) Seeing the spots on this bird in March implied it hatched out in the previous year and was nearing one year old, at the time this photo was taken.

This same Whidbey Island bird was clearly hunting on its own as I watched it eat a small bird and then catch and consume the bat that it was holding in this photo.

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Thank you to Sarah Schmidt who suggested this might be a Big Brown Bat, but she wasn't positive. She explained that there are a total of nine species of bats in our area.

I was also surprised to learn from Sarah about the variety of winter survival strategies among local bat species. One species migrates south when the weather gets cold, some hang around and survive via torpor i.e. slowing their metabolism, and other species choose to hibernate.

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This young female, photographed in the Arboretum in April of last year, was also in her second calendar year, i.e. about one year old, and with spots on her back and yellow eyes. Nonetheless, she appeared to lay eggs, incubate, and hatch multiple young last year. This conclusion was easier to establish because she was caught and banded with an orange bracelet, with the code 8/U, in 2023. Thank you, Martin!

Although this photo does not show perfect proof, I believe this is the same female, because I have repeatedly seen her "8/U" bracelet. Here, she was in the same general area of the Arboretum as last year, but sitting above her new 2024 nest. This year, she once again appeared to lay eggs, incubate and hatch out young. If I am right, it is her offspring you will be seeing in the following photos. Did you notice how at two years old she now has her adult plumage?

Last week, my friend, Jeff Graham, found another way that young Cooper's Hawks interact with the trees, or at least potential trees, in the Arboretum. 

Click Here to see Jeff's video.


The next morning, I also found one of the young stalking pine cones. Apparently, it is great practice for future hunters.

Soon, there were two more siblings, chasing after the first one. I am guessing they might have been wondering, What have you caught? Is it good to eat? Can we steal some? 

The bird in the back is holding its head at a most curious angle. Of course, it is difficult to know if what looks like curiosity in a bird is related to the feeling we have when we hold our heads at an angle.

A few days later I found one of the smaller siblings nearby. The "tell-tail" sign seems to suggest it was eating a rat. 

If you haven't read about rats and the impact of rodenticides please Click Here and review the research being done by the Urban Raptor Conservancy. I also really like the idea that raptors are the solution.

In the same tree on the next branch above it, a larger sibling (probably a female) was keeping a close watch on the feeding process. I was expecting that the upper bird might make a grab for a portion of the food, or push the smaller sibling to the side and take it all.

However, to my complete surprise, the larger bird quietly descended and calmly landed next to the smaller hawk. 

The larger bird then grabbed a bill full of feathers from the smaller bird's chest.

It held the feathers for two or three seconds, which seemed like a surprisingly long time. After it let go both birds seemed to cock their heads to one side as if wondering, "What was that about?"

Next, the smaller bird extended its right wing, but it did not seem like a fearful reaction or an attempt to flee, it looked like it was just regaining its balance. 

Then both birds settled back down and remained seated side by side. I don't know why the second bird grabbed the feathers. Was it allopreening? (Which is when one bird grooms another.) Did the larger bird spot a tiny morsel of food, which it removed from the feathers? Was it really trying to intimidate the other bird and steal some leftovers? I find that unanswered questions are just part of the intrigue, mystery, and allure of nature. 

In any case, these young Cooper's Hawk siblings seem to be amazingly close and friendly with each other.

A few days earlier, I was finally able to get a count of the siblings. Due to the huge crop full of food, i.e. the visible bump below its chin, this one had, evidently, just finished eating. Another was continuing to eat while others were coming and going in nearby branches.

Finally, I caught these three sitting in a single Vine Maple tree, while a fourth stalked among the ferns below. 

At the same time, a fifth sibling continued to eat on a horizontal branch in a nearby tree. 

I am now fairly certain that this year there are at least five young Cooper's Hawks growing up (and occasionally hunting pine cones) among the trees in the Arboretum.

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. 



Is this a native flower? If so, which one is it?











Scroll down for the answer.







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Common Yarrow:

Yes. It is a native plant. There are records of a wide variety of medicinal uses which you can read about by Clicking Here. This same USFS post is also my source for learning that it is sometimes referred to as Milfoil. This must stem from the second half of its Latin name, "Achillea Millefolium" which means "having a thousand leaves." I think the frilly little leaflets in the photo certainly reinforce that definition.






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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