A Population Explosion

Since February, when I first saw the Common Ravens securing nest-building supplies in the Arboretum, I have been watching, wishing, and waiting for young. It may have been more than a century since ravens nested in this area. There is no mention of nesting ravens, or even visiting ravens, in the Arboretum bird surveys I have seen from the 20th century.  

During the last few months, I have occasionally seen ravens heading to the northwest, apparently, searching for food in the mornings and I have sometimes seen ravens at Interlaken Park. More than once, I have seen them returning to the Arboretum from the north, sometimes with food and sometimes without. It feels like I have been hearing ravens almost every time I leave my house. It has been a wonderful change.

Watching their behavior and their participation in our local web of life has been incredibly enriching. At times, it has also been a bit frustrating. For example, these first four pictures, which may be my best ever raven photos, were taken in Interlaken Park on April 29th. Even though, I have spent hours watching the ravens in the Arboretum. It feels like these photographs should have happened there instead. I can't even be sure whether this raven is one from the Arboretum pair or not.

The raven flew in from the northeast while croaking loudly and landed directly in front of me. Every creature in a quarter-mile must have immediately known its location. Since this wasn't the call I have heard the ravens use when chasing away an intruder, I have no explanation for its noisy behavior. (If you Click Here and then pick the first call from Alaska you can hear how it sounded.) 

Still, it was wonderful to see the raven, brimming with confidence. I sure would enjoy some similar disclosures while observing their nesting process. Although, it does make sense that until the young birds learn to fly the nesting process needs to be quiet and hidden. Plus, an adult raven visiting Interlaken Park probably has very little to fear. 

You might wonder if a Barred Owl could threaten a Common Raven. After all, ravens are songbirds and owls are totally meat-eating predators. Barred Owls are the largest resident, predatory, bird I have seen in Interlaken. Even though an owl's wingspan can be nearly as large as a raven's, ravens can weigh significantly more. 

In regards to encounters with Barred Owls, on the evening of April 6th, I took this photo, just to the west of Lake Washington Blvd in the Arboretum. The owl's mate was in a nearby tree. The next morning, I returned to the same area but failed to find the owls. I had just crossed the Blvd when suddenly I heard a raven, clucking loudly. I could not see it through the trees but it sounded like it was heading in my direction.

In a moment, the raven popped out of the trees with an owl briskly pumping its wings while desperately trying to stay in front of the raven. The owl crossed the street just above the traffic and made a beeline for the thick foliage of the Sequoia trees. The raven followed but appeared to be deterred by the profusion of branches. Ultimately, it must have decided that the owl was sufficiently outside of the raven's nesting territory. The raven turned and flew back towards the nest.

A raven's intimidation is not all about being a larger bird. I remember watching one of the ravens who appeared to be standing guard in a treetop about one hundred yards from the nesting tree. From what I have read this means it was most likely a male. It started clucking as soon as it saw a Red-tailed Hawk approaching. A moment later a similar sound came from the direction of their completely hidden nest. Ravens make a variety of sounds and the intruder alert sound reminds me of the noise a chicken makes, which is why I call it, 'clucking'.

The closer the hawk got the faster and more intensely the raven clucked. The raven went directly after the hawk. Red-tails can have a larger wingspan than a raven, however, their weight is fairly similar. On the upside, ravens have the potential to be a few ounces heavier.

In the photo above, the raven is on the right and the hawk is on the left. The hawk is trying to make a quick exit. A second raven (most likely the female) also started clucking and then appeared from the direction of the nest. It followed the first two birds for a short distance. Once the hawk crossed Foster Island Road the 'male' raven turned and followed its mate back towards the nest.

I have seen the same type of hawk intervention happen three different times. In this case, it was further from the nest but it did not change the raven's intensity. The hawk is the one on the bottom, rolling over in defense.

None of the three hawks wanted anything to do with an angry raven.

 

I have also seen the raven chase adult Bald Eagles out of the area, multiple times. Here you can see the eagle is straining to get lift. It was clearly trying to get up and away from the smaller raven.

Yesterday evening, while walking the dog, I heard an unusual number of raven calls coming from the Arboretum. Even though I was without my camera I could not resist the opportunity to observe ravens in action. I found three of them flying around the treetops, calling loudly. I thought one or more sounded young, but I could not see clearly enough to be sure.

Early this morning, I returned without the dog and with my camera. The ravens did not disappoint. I crossed paths with my friends, Rick and Anne, on Azalea Way. Suddenly, two ravens descended to the ground while attempting to evade the harassment of an American Crow. The ravens quickly returned to the treetops but I did see that one was carrying food.

About forty-five minutes later, I finally documented one of the adults feeding its fledgling.

A few minutes after that, I found two young - clearly wanting more food from the adult. When these birds are in flight, flashing about among branches and trees, with varying numbers of similarly black crows giving chase, it can be very hard to determine what you are seeing. Photos are helpful. 

By the way, Common Ravens and American Crows are both Corvids which explains why they look so similar. You can compare their differences in my previous post, The Mythical Raven.

In addition to the begging behavior, the photo above allows us to see some other indications of youth. For example, their red gapes. With the bird on your right, you can see just a small hint of pink at the joint where the bill hinges. With its sibling, the bill is opened wider and the pink has become more visible. Also, in the middle of the sibling's lower jaw, you can see a glow of red where the light shines through a thin membrane. I suspect when the bird is mature this area will be obscured by feathers.

The two young follow each other from tree to tree while waiting and begging the adults for food. Sometimes, they squabble just like human siblings. Earlier, I saw one pluck a downy feather off the chest of its sibling. The second bird immediately grabbed the closest piece of the feather and for a moment it looked like a tug-of-war with the offended bird wanting its feather back.

Still, on the whole, they appear to be similarly sized and genuinely enjoy each other's company. Birds of the World (BOW - citation below) lists a wide variety in the amount of time young fledglings hang around with their parents. It can be as short as a week or until winter has passed. In BOW there is even mention of an occasional third bird helping during nesting. I wonder if it might be an offspring from a previous year?

It will be very interesting to watch and see what happens with these two young ravens. It has already been over a week since I first saw one of them out of the nest. The next time you visit the Arboretum I would suggest bringing binoculars if you want to have a chance to closely observe these noisy young birds.

As I was leaving the Arboretum, I walked through the Pinetum. In the last year or two, I have seen multiple crow nests in the area. As I passed this pine tree, the crows were diving, calling, and mobbing this adult raven. The raven finally gave up and headed back toward its territory. The crows calmly returned - once the raven was east of Lake Washington Blvd. It made me realize that the raven was probably attempting to raid a crow's nest. I wonder if our growing abundance of crows in the city is the primary food source that has encouraged the ravens to return? If so, I suspect we will see an exploding population of ravens in the future. 

Actually, if our human population doubled we would call that an explosion. With the local raven population going from two to four maybe we are already in the midst of a population explosion.

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

Larry 

Recommended Citation

 Boarman, W. I. and B. Heinrich (2020). Common Raven (Corvus corax), version 1.0. In Birds of the World (S. M. Billerman, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.comrav.01

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 our local environment and native creatures. I have been told that 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 to 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. (If natives 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.

My intention in my weekly post is to include at least one photo each week and visually challenge us to know the difference between native and non-native lifeforms. 

What species is this? Is it native to Western Washington?

Scroll down for the answer.

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Horse Chestnut: This common tree is not native. Its fruit is considered poisonous and, I suspect, a native Big Leaf Maple might grow very nicely in many similar circumstances.

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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 workaround is to set up 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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This photo is a little reward for those who have read all the way to the end. 

Raven's tails do not always show their characteristic 'diamond' shape, however, their wings are always relatively longer and less rounded, as compared to a crow, plus ravens are less likely to rapidly flap their wings.

An Exotic Flair

A clear view of a male Western Tanager is startling. You can be forgiven for thinking that a Tanager is an exotic bird with a misguided sense of direction. They do winter in places like Costa Rica, Honduras, El Salvador, Guatemala, and Mexico. However, in the Spring, they follow their ancient impulses and head north. Their migratory path covers both sides of the Rocky Mountains and all the way west to the coast. All of their breeding and reproduction happens in the western portion of North America. So, maybe we should say, they are native birds with a taste for exotic winter vacations.

All About Birds quotes Partners In Flight who estimate the Western Tanager population around eleven million. Even if only one percent pass near Seattle that would still be over one hundred thousand birds. 

Why don't we see more of them? For one thing, they often migrate at night which is no doubt their safest way to travel. Thousands of bright yellow birds with redheads migrating during the day would be an amazing sight, but I suspect they might be easy targets for predatory birds.

During Spring their dietary focus is on eating insects. They do most of their hunting in the treetops, which is another reason we seldom notice them. Also, their yellow color actually blends surprisingly well with the fresh sunlit leaves of Spring. 

I suspect that this was a crane fly. (Chemicals that get rid of insects in our yards and trees  are effectively stealing food from the birds and poisoning the ecosystem.)

Plus, roughly half are female. Unlike the males, they do not have brightly colored faces.

Their greenish-yellow color could be considered nearly perfect camouflage, especially, when perched among the winged seeds hanging in a Big Leaf Maple tree. Tanagers often perch for a moment while they check out their surroundings for insects.

Birdweb says, that during their first-year male Western Tanagers tend to have less red on their faces. Tanagers are thought to get their red coloring from the food they eat. Apparently, the amount of red varies due to diet and, evidently, accumulates over time. Having less red probably makes them less appealing to females. It certainly makes them a bit less conspicuous to us. 

I have not found any documented link to a known food source that supplies the red coloring. There are suggestions that they might get the coloring from insects. However, there is no mention of which species. It is amazing how much we still have to learn about the creatures around us.

There is one more important reason we do not see as many tanagers as we might expect. For many of them, Seattle is more like a truck stop than a destination. They are simply refueling before heading further north to nest. Click Here to see their North American breeding territory on All About Birds. 

Although they can nest high in the mountains, some do nest in nearby rural areas. My friend, Dan Pedersen, has had a pair nesting near his home on Whidbey Island for several years.

The earliest arrival, I have heard about this year, was at this birdbath belonging to my friends, Anne and Rick. (I truly love this great photo taken by Rick.) This Western Tanager arrived on April 26th and was joined by a female about a week later.

This year, my first sighting of a Western Tanager was on May 1st, about two hours later than last year. I have read reports from friends all over the city who suddenly noticed Western Tanagers on the same morning. May is most certainly the month to break out your binoculars and search the treetops for Western Tanagers.

The next few days were a bit cooler and I didn't see any more until suddenly on May 4th, which was a nice sunny morning. I stood for hours taking these photos and enjoying the rush of exotic colors.

A curious bit of information I just learned on Seattle Audubon's Birdweb is about the gender-based difference in their wing bars. Males have a bright yellow wing bar above and a pale bar below. Isn't funny how we can look at a bird or a photo and not notice something perfectly obvious until it is brought to our attention.

Females have two pale wing bars. They are often white or may contain a very slight yellow hue.

Another interesting point on Birdweb was the discussion of the Tanager's bill size. It is heavier than the bills of birds that specialize in insects, while lighter than the bills of birds who eat primarily seeds. In the winter, Western Tanagers are said to eat fewer insects and more fruit. Apparently, their mid-sized bills are a compromise that enables a more varied diet. 

I also find the shape of their bills helps identify the female Tanagers. Most other primarily yellow-green birds, that I see, have noticeably smaller bills. 

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

Larry

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 our local environment and native creatures. I have been told that 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 to 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. (If natives 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.

My intention in my weekly post is to include at least one photo each week and visually challenge us to know the difference between native and non-native lifeforms. 

What species is this? Is it native to Western Washington?

Scroll down for the answer.

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Douglas Squirrel: The Douglas Squirrel is native to our area. However, this is the first one I have ever photographed in our Union Bay neighborhood. My friend Kathy mentioned seeing one a few months ago but it has taken time to find it and get a photo. I have spoken to neighbors who say they remember seeing them decades ago. It is wonderful to have at least one returning to our area. By the way, they love pine trees, which is where I found this one.

Eastern Gray Squirrels are now our most common squirrel seen around Union Bay. They were introduced from the eastern portion of North America. A few easily noticed differences include primarily gray versus more of a brownish-gray, white bellies versus yellowish-orange, and the lack of ear-tufts on the Eastern Gray Squirrel. Mature Eastern Grays are also larger plus their tails are bigger, fluffier and lighter.

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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 workaround is to set up 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

***************

This photo is a little reward for those who have read all the way to the end. I watched while this male Dark-eyed Junco took these little inchworms to the nest. The nest was on the ground hidden under Creeping Yellow Buttercup. (This time of year off-leash pets can easily sniff out the Junco nests and quickly consume their young.)

Eaglet Patrol

Marsha in her newly refurbished nest above Montlake Cut.

By mid-April, Monty and Marsha's behavior around the nest was beginning to change. 

Tyler, a Union Bay Watch reader, sent an excited email on April 20th. He was nearly certain he could see the eagle's behaving as if their eggs had hatched. The situation was a stark contrast to earlier in the month - in more ways than one.

On April 3rd, the eagle's were still taking turns sitting low in the nest, apparently, incubating eggs. While Monty was searching the cold gray skies for any signs of danger, he may have also been wondering when Marsha would return and take the next shift.

By mid-April, the green leaves, the blue skies, and the eagle's evolving interest in the nesting process were all encouraging signs of spring.

One obvious behavior change was when the adults start bringing food to the nest. Even though the eaglet(s) were too small to be seen from the ground the adult's new behavior was fairly obvious. Prior to nesting season, the adults often eat on reasonably-sized, horizontal portions of nearby branches. Once they start feeding young, the adults will often finish the leftovers while still in the nest. Later, as the eaglets grow, the leftovers shrink, the inept young birds may become a bit dangerous. The adults revert to eating elsewhere.

During what looked like a feeding session in the nest, Marsha got something temporarily stuck on the tip of her bill. It may have been a twig from the nest or some inedible portion of the meal. 

In either case, it looked a lot like she was feeding an eaglet.

Our big questions for this year are: 

• How many young will Monty and Marsha have? 
• How soon will we see them? 
• When will the young learn to fly - or fall? 
• Will the nest stay in the tree? 

This is Monty and Marsha's third year nesting above Montlake Cut. They are in the first tree south of the totem pole. If you want to see them be sure to bring binoculars. Due to the angle of the nest and the proliferation of cottonwood leaves, the best viewing may actually be from the north side of Montlake Cut.

In 2018, a branch broke, the nest fell and both young ended up on the ground and unable to fly. With help from the Progressive Animal Welfare Society (PAWS) and others, both young survived and were released to the wild. 

In 2019, one of their two young fell from the tree, he was uninjured and, again with help from PAWS, he was reunited with the adults. So far, often with help, all of their young have survived long enough to learn to fly.

After considerable use (for flight practice, landing pad, and dinner table) the remnant of the 2019 nest could have been easily mistaken for the work of a crow. This photo was taken in November of last year, around the time the adults began their reconstruction.

By April, after an extensive effort, the nest was many times larger, hopefully, much sturdier and, hopefully, holding a full set of eggs.

Last Sunday, on my way over to check for eaglets, I noticed an osprey searching for fish in Kingfisher Cove. The cove is a shallow bay, south of 520, and just southeast of the eagle's nest. The cove is completely enclosed by the WSDOT 520 bridge construction and staging areas.

A short time after I arrived at the eagle's nest, Marsha spotted the osprey. Apparently, she felt the osprey was a threat. I do not know why. Ospreys normally eat only fish. I have never heard of them being a threat to an eagle nest. Although, I suppose Marsha might have simply wanted to protect the supply of fish in their territory. Monty and Marsha's territory normally includes Kingfisher Cove, Marsh Island, the southwest portion of Union Bay, Montlake Cut, and Portage Bay.

Quickly, she left the nest and headed directly towards the osprey. The smaller bird began circling up higher and higher into the sky. Marsha circled below, slowly gaining altitude while driving the osprey ever upward.

 

Monty was sitting just a few feet above the nest and peering intently into it.

After a time, he jumped down to the nest and began removing morsels from the remains of a previous meal. That was when I first saw the small fuzzy head of a young eaglet just to his left.

If the eaglet hatched out in mid-to-late April, I am guessing it will fledge sometime in the first half of July. Independence Day would certainly be a fitting time to begin to fly.

The eaglet is so small and distant I was unable to get my camera to actually focus on it.

When Marsha returned after banishing the osprey, Monty had already left the nest.

The size difference between the eaglet and Marsha is incredible. If we average the weight range of adult eagles given on All About Birds it comes out to about ten and quarter pounds. Females are actually larger than males so Marsha may weigh even more. If we average the weight of eagle eggs listed on Birds of the World (citation below) they come out at about one-quarter of a pound. Even if the eaglet has been eating for a few days, It may have weighed less than a pound when this photo was taken.

Later, after Marsha settled in and the eaglet disappeared from view, a first-year eagle passed overhead.

 

Marsha raised a ruckus and Monty immediately gave chase. After two rather aggressive dives, Monty circled back towards the nest tree.

The immature eagle circled around for a last look before leaving the area. 

We now know there is at least one eaglet in the nest. There could be more. They may still be too young to walk around. Even the first one has been nearly impossible to spot as the week progressed. We also know Monty and Marsha are on active alert. The eaglet patrol is strongly defending the nest site. 

Curiously, this strict attention to the nest area means the outer realm of their territory is not being defended as much as it was during winter. In a sense, you might say that Monty and Marsha are sheltering-in-place. Their family focus means intruders may have more time to hang around and hunt in Portage Bay, at the far end of Marsh Island or even at Kingfisher Cove. I think this may be part of the reason we notice more immature eagles around Union Bay during this time of year. Migration also plays a factor. For example, the Ospreys have begun returning from their warm winter locations.

Once the young can feed (and to some degree protect) themselves the adults will switch to delivery only. By that point, the white young bird will have grown a less-inspiring cloak of gray feathers. By the time it learns to fly the gray will be replaced by mostly dark feathers speckled with white. Finally, four or five years later, the young eagle's head will turn white once again when it is ready to settle down, take a mate and reproduce.

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

Larry

Recommended Citation:

 Buehler, D. A. (2020). Bald Eagle (Haliaeetus leucocephalus), version 1.0. In Birds of the World (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.baleag.01

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 our local environment and native creatures. I have been told that 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 to 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. (If natives 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.

My intention in my weekly post is to include at least one photo each week and visually challenge us to know the difference between native and non-native lifeforms. 

What species are these? Are they native to Western Washington?

\

Scroll down for the answer.

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Painted Turtle: The smaller turtle is a native Painted Turtle. For more information Click Here.

Red-eared Slider: The larger turtle is native to the lower Mississippi Valley and neighboring areas. For more information Click Here. I zoomed in, in this second photo, to try and make the 'red ear' a bit easier to see.

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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 workaround is to set up 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

***************

As a reward for reading this far here is a photo of Monty from last Sunday, sitting on a log along the edge of Union Bay. It looks like he is considering a swim, but actually, I think he is watching some noisy gulls approaching from the south.