Dark-eyed Juncos are common around Union Bay. Wherever you walk there are likely to be Juncos somewhere nearby searching for food, most often on the ground. We also see them in trees, but I tend to notice them most when I startle them and they fly off to a nearby bush, tree or just a slightly more distant spot on the ground.
The earth tones in their plumage blend well with dirt, gravel and dried leaves. One of their most notable features, their light-colored bills, contrast nicely with their dark hooded heads.
The males have crisp black hoods...
When they fly away, their tails flicker and expose another notable feature, their white outer tail feathers. These feathers help to distinguish them from other birds and help identify them as Dark-eyed Juncos.
During much of the year, Juncos eat seeds, as in this October photo.
Here, one of the small winged seeds from the Birch tree is clinging to the bird's wing, while the Junco searches for more. When they, or other species like House Finches, are finding seeds in the trees, there are often even more Juncos on the ground below picking up the seeds that have already fallen.
In June, before the tree seeds are ready, Juncos will consume grass seeds.
Earlier still, in April, Juncos focus more on protein, but often not for personal consumption. April is "Catch and Carry" time as they secure food for their young in their nests.
The bird in this photo is removing a small greenish caterpillar from a Big-leaf Maple tree. As Professor Tallamy suggests caterpillars are probably the most critical and nutritious food source for young birds. (See the Go Native section below to learn more about the Keystone plants and trees that support caterpillars and therefore young birds.)
Imagine the nutrition in this caterpillar as compared to a tiny seed.
From the time the eggs are laid until the nestlings are ready to leave the nest is less than a month. Dark-eyed Juncos normally make their nests on the ground. After the eggs hatch, the young are unable to fly and hidden nests increase their odds of survival.
While the young are in the nest the parents bring food almost nonstop. The young need to quickly gain weight, develop strength, leave the nest, and learn to fly to evade potential predators.
A partial list of the creatures that might willingly consume Junco eggs, nestlings, or even the adults includes: Norway Rats, Cooper's Hawks, American Crows, Stellar's Jays, Squirrels, Barred Owls and off-leash Dogs or Cats.
In addition to these creatures during Spring weeding we, humans, may accidentally disturb their nests. Simply uncovering a nest may cause the adults to abandon it.
Since April is a prime time for both nesting and weeding, I suggest spending time watching the behavior of birds in your yard before beginning your Spring yard work. If you notice a bird carrying something, in early Spring, it will often be headed towards its nest site.
Initially, they carry nesting material.
Later, they begin carrying food for their young.
In addition to finding well-hidden caterpillars...
...they also catch insects.
Normally, Juncos hide their nests under fallen leaves, piles of branches, ivy, sword ferns or other vegetation. Occasionally, they nest in trees. If you notice ground-nesting behavior, avoiding the area until the young have fledged, is a wonderfully gracious idea.
Less than two weeks after hatching, the young leave the nest and begin following the parents. They are still being fed while also learning how to find food. Initially, their ability to fly is limited.
I suspect the short tail, of the young bird on the left, provides less control during turns and landings. I would bet the growth of their tails, correlates with the refinement of their flight skills.
In addition to the challenges above, occasionally, nesting Juncos also face another issue.
Brown-headed CowbirdsOriginally, according to All About Birds, Cowbirds followed the Bison herds on the Great Plains. As the Bison disturbed insects in the grass and caused them to fly, the Cowbirds would feed on the insects. (Maybe we should be calling them Brown-headed Bison-birds.)
The female Cowbird must be a surprisingly intelligent creature. The Cowbirds have evolved to lay their eggs in the nests of other, typically smaller, birds. Thereby, they avoid the work of nest building, incubation, and feeding young. This nesting approach may have developed because of the Cowbird's need to keep up with the Bison. Since the Bison were constantly moving to find more grass, the Cowbirds needed to keep moving and did not have time to stop and nest.
Research referenced in Birds of The World (citation below) says female Cowbirds find host nest sites by one of three methods. The "female may perch quietly in the tops of shrubs or trees and silently watch for nest building activity in the surrounding open areas; female may walk on ground, looking about and watching for movement of other birds; or female may employee a noisy searching method of short flights between vegetation with landings in leaves accompanied with wing flapping as if intentionally trying to flush potential hosts from nests."
By sticking with the Bison the Cowbirds would have had an abundant supply of insects which would provide the required nutrients and minerals to lay an abnormally large quantity of eggs. There are not too many Bison, flushing up insects, around Union Bay for the Cowbirds. Maybe our bird feeders are helping to fulfill their need for food.
In any case, a Cowbird successfully fooled this Dark-eyed Junco and its mate. In 2022 this Junco, and probably its mate, must have invested a major portion of their breeding season incubating, feeding, and raising this young Cowbird.
Today, the Cowbirds around Union Bay, even without the inspiration of Bison, continue to lay eggs in other bird's nests. This creates a variety of inadvertent foster parents. Birds of the World references the work of Herbert Friedmann, who determined that 144 different species of birds have been known to raise Cowbird nestlings.
Sometimes, the Cowbirds will even remove some of the host's eggs from the nest. Also, a young Cowbird bird, with genetics to become a relatively larger bird, will often out-compete the host family's young. The Cowbird's utilization of host species is called parasitic brooding. From a human perspective, it is a cruel trick, however, if viewed from the perspective of evolutionary complexity, it is an incredibly amazing adaptation.
Dark-eyed Juncos are so plentiful that, even though a female Cowbird may lay as many as 40 eggs a season, the Cowbirds are not likely to be a threat to the survival of Dark-eyed Juncos - as a species. However, there are other endangered species, where human development, climate change, or other factors have already reduced their numbers. For these, Cowbirds could end up being the final factor. In my opinion, the challenge for humanity is not the removal or reduction of Cowbirds. I believe we should be enhancing our yards, cities, parks, beaches, and shorelines so that all species of birds can, occasionally, raise a Cowbird without endangering their species' survival.
Have a great day on Union Bay...where nature lives in the city and Black Birders are welcome!
Larry
Recommended Citation
Lowther, P. E. (2020). Brown-headed Cowbird (Molothrus ater), 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.bnhcow.01Going 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.
***************
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:
Additional content available here:
https://wos.org/wos-wp/wp-content/uploads/2022/10/Native-Plant-Resources-10-7-22.pdf
******************
Typically, in the area below, I display at least one photo with each post to challenge us to know the difference between native and non-native lifeforms. This week I took a slightly different twist related to the parasitic theme.
Are lichens parasites? Do they steal nutrients from trees?
Scroll down for the answer.
******************
Last week I had the opportunity to learn from Katherine Glew and Carl Baker that lichens are epiphytes, i.e. they use the trees, and other objects for support, but are not parasitic. They gain the moisture and nutrients they require from the air.
In the excellent text, "Macrolichens of the Pacific Northwest", by Bruce McCune and Linda Geiser, on page xii of the second edition the authors state, "...a lichen consists of a fungus and its photosynthetic partner (green algae, cyanobacteria, or both) growing together in a mutually controlled, symbiotic relationship..."
Lichen are used for food, homes, and nesting material by a wide variety of insects, birds and other creatures.
(On page xiii of the book is a very interesting paragraph that describes the mutually reinforcing relationships between Brown Beard Lichen, Flying Squirrels, Spotted Owls and the trees of old growth-forests. It refers to the works of C. & Z. Maser in the mid-1980s.)
Our class learned that there are three major groups of lichen. There are crustose which are crust-like, folliose which are leaf-like, and fruticose which are thin and have branches that look some what like a fruit tree.
Carl says, "It's difficult to identify specific lichen by photograph, but the majority of the lichen present here looks to be a fruticose lichen whose scientific name is Evernia prunastri and likely a species of lichen of the genus Usnea as well." (I, Larry, understand the Usnea to be on the upper right and below it on the far right is a bit of foliose lichen.)
Note: This lichen was found on the ground. It is best not to remove lichen from a tree, rock, or other surface since losing its support is likely to shorten its life (or lives). When you find a fallen piece, it is good to leave it where its nutrients will be recycled and used by other organisms.
A special, Thank You, to Carl Baker for all of his guidance and patience!
*****************
The Email Challenge:
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!
*******************
The Comment Challenge:
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
Larry
No comments:
Post a Comment