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.)

A:

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

B:

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: