Showing posts with label American Robin. Show all posts

Sunday, January 3, 2021

Reliquias

A Varied Thrush searching for Autumn fruit.

In the Fall, when the Sorbus, or Mountain Ash, berries are ripe their brilliant color attracts hungry birds. American Robins boldly raid the trees in the Arboretum and occasionally their relatives, the shy Varied Thrush, slip out of the shade for a mouthful of fruit.

It can take multiple attempts to soften...

...and swallow a particularly large piece of fruit.

The red berries vanish as November turns into December.

In December, a few of the Sorbus trees were still heavy with fruit, but only the ones with white berries. The colorless fruit did not look ripe, despite its size.

Most, if not all, of the Sorbus in the Arboretum, did not originate in North America.

Locally, the only native white berries I know about are Snowberries. They often hang on the bushes, uneaten, while slowly turning brown.

Curiously, All About Birds does mention that Varied Thrush will eat Snowberries in the Winter. I wondered if they would notice the white Sorbus berries?

A Varied Thrush investigating the 'leftover' fruit.

By the way, take a moment to compare the bird in this photo with the one in the photo below. What differences do you see?

The bird with the berry is black on the face and chest and slate-gray on the back. This indicates it is a male. The upside-down bird in the previous photo has a lighter brown color in all of these locations. It is female.

Could it be the size or the smell of the colorless berries that attract the birds? This episode from Birdnote provides an interesting perspective regarding birds and their taste buds. In either case, it is probably the taste that keeps them coming back.

Often, when another bird approaches, a stationary bird will take its fruit and fly.

Surprisingly, the slightly smaller Varied Thrush 'stood its ground' in the face of this American Robin.

Robins are common all across the North American continent. During the breeding season, many migrate north to Canada and Alaska. During winter they tend to congregate in the Lower 48 states and northern Mexico.

Varied Thrushes are normally found only in the west. Usually, in a relatively narrow band running north from California and up into Alaska. Their range map appears to indicate that they migrate north and south, but if you look closely you will notice they tend to winter at lower elevations, often in places warmed by air flowing in off the Pacific Ocean. Since they breed in more elevated places, like the forested slopes of the Cascade Mountains, their migration may actually be related more to elevation than latitude.

When not eating fruit, Robins can often be found searching for worms in our yards and parks.

When Varied Thrushes are not eating fruit they are more likely to be seen searching the shade below a stand of coniferous trees. They will often be softly lifting the leaf litter in their search for sustenance. I suspect they are looking for insects and grubs.

The slightest motion or noise can cause Varied Thrush to flush, so, if you go looking for them in the forest, don't look too loudly.

The same thing is true when they are eating fruit.

While a Robin might ignore a quick movement or a sudden sound, a Varied Thrush will fly.

Fruit-eating birds can be classified as Frugivores. This term originated from the Latin words meaning, "To devour fruit".

Of course, nature is never simple.

Berries are not available year-round plus dietary needs certainly change depending on the season.

For example, while creating eggs females require considerably more calcium than they will need later in the year.

This worm was most likely motivated to wiggle its way to the surface by the rain permeating the soil and a growing need to breathe. The Varied Thrush leaped from the Sorbus tree, ignored the fallen berries, and focused on the worm.

It is not breeding season, and this bird was not a female, so it was not accumulating calcium for eggshells. Maybe, after all the fruit, it was just hungry for protein. Still, it made me curious about how females collect all the calcium they need.

Click Here to read an account regarding birds and calcium in the UK. What I found most interesting was the statement that the soil in the gut of the worms may actually provide a considerable portion of the required calcium.

If fruit-eating creatures are frugivores then what classification do we give to worm-eating birds? It turns out the appropriate term is "vermivore". In Latin, "Vermis" means worms so obviously, vermivore means, "To devour worms".

It is probably not an accident that the word "worm" sounds so similar to "verm". As long as we are on the subject of linguistics, it is also curious how our common understanding of the word "vermin" seems to be evolving away from the original meaning.

When scratching through the leaf litter and consuming primarily insects a Varied Thrush becomes an insectivore.

Clearly, classifying birds by what they eat could be modified by the time of year, food location, their dietary demands, and even the method by which they gather their food.

Dennis Paulson sent me this interesting link to research concerning the different foraging techniques utilized by birds. The authors sort the birds into guilds - which are groupings of birds that find food in similar ways. It is my intention over the next year to expand our knowledge by utilizing the appropriate terms with each new episode.

For example, Varied Thrush may be primarily considered, "ground-gleaning insectivores". However, sometimes, it could be more appropriate to call them, "upper canopy-gleaning frugivores" and occasionally "ground-gleaning vermivores".

Cedar Waxwings are an example of another avian species that can sometimes be considered a member of the "upper canopy-gleaning frugivore" guild. Click Here to see an example.

At other times, they can be better described as "air-sallying insectivores".

If fruit is available, American Robins are "upper canopy-gleaning frugivores", however, much of the year they are "ground-gleaning vermivores".

In 2021, I hope you will continue to join me while we expand our joy and understanding of nature.

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

Larry

ps: Reliquias is Latin for leftovers.

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.

(By the way, my friend Tom Brown pointed out that the application named 'Wildflower Search' is extremely helpful. Click on the highlighted link to see for yourself.

Also, Jane Lundin has created a small package, with a lot of critical information that looks quite handy, and light, for backpacking in the mountains in Springtime. It is titled, Mountain Wildflowers of Washington.)

Is it normal to see this young bird around Union Bay in July?

Scroll down for the answer.

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A = American Robin: Yes. American Robins nest and reproduce all around Union Bay e.g. in our yards, parks, and of course the Union Bay Natural Area.

B = Varied Thrush: No longer. Varied Thrushes tend to nest and reproduce in forested areas, away from the city and at higher elevations. (This photo was literally taken in the center of the Olympic National Park.)

Note: Birdweb mentions that historically Varied Thrushes did nest in the Puget Sound lowlands. All About Birds mentions that they usually require a forested area of at least 40 acres in which to build their nests. This implies that the lack of lowland forests, e.g. human development, has pushed their nesting away from Puget Sound, including our Union Bay habitat.

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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

A few more final photos:

Saturday, January 11, 2020

A Winter Thrush

When we sense danger, like a bird, we may freeze for a moment. Our adrenaline pumps, our minds race and we rapidly consider alternative strategies of escape. I suspect the experience for birds is similar - but more intense. Since they are smaller than us, they have more to fear. Internally, I suspect they vibrate at a higher speed. I wonder if the average bird feels like a human who has consumed six cups of fully caffeinated coffee. Their survival depends on their constant awareness and split-second decisions.

(When we startle a bird the best thing we can do is nothing. Don't move, don't make a noise, don't even stare. Wait and watch - out of the corner of your eye. When the bird returns to feeding, or whatever it was doing, then quietly and slowly move on or assume a more relaxed position.)

Varied Thrush reproduce in forests, preferably old-growth forests. They are accustomed to clean air, dappled shadows, cool floating mists and silence. The city seems like an odd place to find them and yet they are often here.

The American Robin, also a Thrush - e.g. a member of the Turdidae family - is a relative of similar size and color. In the fall, the Varied Thrush can occasionally be spotted in the city feeding with Robins on the same types of fruit. Given their preference for quiet the Varied Thrush are likely to be a bit more in the shadows and often further away then the Robins. They are elusive and shy.

September 30th is one of my earliest fall photos of a Varied Thrush.

Even in October, the Varied Thrush still looks a little out of place when photographed in front of bright green leaves.

However, the fruit they find in the city must be virtually irresistible.

By mid-November, the leaves are turning to autumn colors.

The Varied Thrush blend in beautifully among fall leaves. The male birds tend to have more black coloring, which I find most obvious around the face. (This is also true for American Robins.)

Among females, their 'black' coloring has more of a faded, brownish tone. No doubt it helps them blend in with their surroundings.

In my experience, I find the Varied Thrush generally silent during the late Fall and Winter. However, in the early Autumn, when walking through the Arboretum just after dawn, you can often hear their lonely, heartbreaking songs. The sounds transport me to the dim, sanctuary of an old-growth forest. These are the songs I would expect to hear on distant mountains especially during the early part of the breeding season.

To me, the piercing song sounds like two gentle notes, just a half step apart and perfectly even in volume, and yet softly fighting for vibrational dominance. If you Click Here you will be transported to All About Birds where you can play a Gerrit Vyn recording. The second and third sets of tones seem most similar to our local birds. (For some odd reason if you want to replay the song more than once you must reload the page.)

In December, after most of the leaves have fallen, the Varied Thrushes are somewhat more obvious.

Their beauty feels like nature's reward for being out and about in cold, wet weather and looking closely at every bird which gives the cursory impression of being an American Robin.

By late December, the available fruit has diminished.

By January, the fruit is looking like raisins that have passed their prime.

I love this photo of their 'fruit-eating' tongue. It looks exactly like the tongue of a Cedar Waxwing and serves the same purpose. The 'fish hook' on the back of the tongue helps to push the fruit down their throats.

My latest in the year, city-photo of a Varied Thrush, shows a female on March the 4th. Which fits with the idea that males leave first to find and defend their breeding territories. Birds of North America states that 'Males arrive on breeding grounds earlier than females and begin singing almost immediately to establish territories.'

The earliest reference given for this quote refers to, 'Jewett, S. G., W. P. Taylor, and J. W. Aldrich (1953). Birds of Washington State, University of Washington Press, Seattle, Washington, USA.'

My friend and Master Birder, Dave Galvin, has noticed Varied Thrush appearing in the Cascade Mountains in late March and early April. He calls this vertical migration. Birds of North America concurs. It states, 'In much of its range, it appears that naevius (the coastal subspecies) migrates attitudinally from lowland areas to adjacent coastal mountains, but some north-south migration occurs as well.'

Seattle Audubon's Birdweb (under the 'Find in Washington' tab) shows that the Varied Thrush becomes uncommon in the Puget Trough between May and August. Since during the last few years I have seldom been in the mountains, I did not expect to find any breeding season photos of Varied Thrush in my database. However, in July of 2017, my friend Rob Thomas and I hiked through the center of the Olympic Mountains.

Near Low Divide, elevation 3602', I photographed this young Varied Thrush. Notice how the feathers are short and of uniform length. Mature birds do not generally grow all new feathers at the same time. The brown coloring may indicate it is a female or it might be a young male who has not yet achieved breeding age or plumage.

Even young birds need to keep their feathers properly arranged and clean.

By visiting All About Birds, and scrolling down to the Conservation heading, you can see that Varied Thrush species have decreased in abundance by 73 percent between 1966 and 2015. This correlates with a decrease in old-growth forest, their prime breeding habitat.

When we protect the forests around us we protect the richness of our life experience and that of future generations as well.

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

Larry

Recommended Citation

George, T. L. (2000). Varied Thrush (Ixoreus naevius), version 2.0. In The Birds of North America (A. F. Poole and F. B. Gill, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bna.541

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.

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

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.

Is this tree native to the Pacific Northwest? What species is it?

Scroll down for the answer.

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Western Hemlock: It is a common native tree that occurs generally to about 3500 feet, close to the elevation of the Low Divide in the Olympics. However, from what I read about the Olympics on Wikipedia, in the drier central and eastern portion of the Olympics, e.g. west of Mt. Olympus, Western Hemlocks extends significantly higher.

In general, the easiest way to distinguish the Western Hemlock from the Mountain Hemlock is the size of their cones. The Western Hemlock cones are generally less than an inch in length while the Mountain Hemlock cones are usually longer than an inch. Although, since no cones are visible in this photo, this difference is not very helpful in this particular instance.

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The Email Challenge:

My email address is: LDHubbell@Comcast.Net