I wish each and every Naturally Curious reader a holiday season filled with joy, laughter, kindness, compassion and love. If you need confirmation that there is still goodness in this world, find a two-year-old…their innocence and joy is undeniable and irresistible! (Photo: Otis Brown)
Naturally Curious posts will resume on January 3rd.
The latest Mystery Photo is of an ice disc – a large disc of ice spinning in a river. It’s thought that this relatively rare natural phenomenon is likely caused by cold, dense air coming in contact with an eddy in a river, forming discs ranging anywhere from 3 to 650 feet in diameter.
While eddies contribute to the spinning, they are not the only cause. If they were, small discs would spin faster than big discs, and this is not the case. Discs of all sizes rotate at roughly the same rate. One would also expect that discs in still water, where there aren’t any eddies, wouldn’t start spinning, but they do.
The melting of the ice disc contributes to its spinning as well. When an ice disc starts to melt, the melted ice water is denser than the ice, and thus sinks below the disc. This movement causes the water to spin, which in turn spins the disc. (Thanks to Martha Kent for photo submitted by Paula Kelley)
What do you think is going on here? Answers should be entered under “Comments” at the bottom of this post on my blog at www.naturallycuriouswithmaryholland.wordpress.com. (Photo by Martha Kent, Winooski River, Richmond, VT on 12/15/17)
On another note: I have recently received a number of inquiries regarding how one can donate to my blog. Everyone has been so generous with my daughter and grandson’s fund that I have hesitated to put a donation option back on my posts, but I have been encouraged to do so and it will return in January. Meanwhile, in response to those who have recently inquired about supporting my Naturally Curious blog with a donation, you can go to www.naturallycuriouswithmaryholland.wordpress.com and click on “Donate,” or send a check made out to me to 134 Densmore Hill Road, Windsor, VT 05089. Thank you so very much.
The Polyphemus Moth is a giant silk moth, a member of the Saturniidae family which includes some of the largest species of moths. Giant silk moths derive their name from both their size as well as the fine silk they use to spin the cocoons which serve as protection for the pupal stage in their life cycle.
Most Polyphemus Moth cocoons start out attached to a tree branch, although some are spun among leaves or grasses on the ground (see pictured cocoon). They are oval, roughly 1 ½” long and nearly an inch wide. Cocoons in trees are susceptible to attack by squirrels and woodpeckers, whereas mice are the biggest threat to cocoons on the ground.
The moth overwinters as a pupa inside the cocoon. Unlike most other giant silk moths’ cocoons, the Polyphemus Moth cocoon lacks an escape “valve” at one end. In order to emerge (as an adult) from the cocoon the summer after it spins it, the moth secretes an enzyme that digests and softens the silk at one end. Then it moves about the cocoon in a circular pattern, tearing the softened silk with two spurs located at the base of each wing on its abdomen. Eventually it escapes by splitting the silk and pushing the top up.
To start with the basics, both the excretory anatomy and the consistency of bird droppings are different from those of most mammals. Birds have one opening, a cloaca, which serves as their intestinal, reproductive and urinary tract. Everything from mating and laying eggs to voiding waste takes place via the cloaca.
Instead of releasing waste as urea dissolved in urine, as we do, birds excrete it in the form of uric acid, which is the white liquid we associate with bird droppings. Why is it white instead of brown? This is due to the biochemical reactions that take place in processing the waste so it can be safely excreted with minimal water loss.
If you look carefully at a bird’s droppings, you’ll usually find a small dark solid blob amongst all the white uric acid. Both acid and solid waste are evacuated from the same opening at the same time. Because they come from two different bodily systems, they don’t have much time to blend.
Most people are not great fans of bird droppings due to the damage (and mess) they can cause. However, some ingenious soul took advantage of this property and concocted a skin exfoliator for sale that consists of nightingale droppings, water and rice bran.
(This post is dedicated to my sister who didn’t quite believe I would actually write a post about this subject much less use this Snowy Owl photograph.)
Only Naturally Curious readers would come up with flossing!
If lemmings are in short supply and you’re a Snowy Owl, head for tall grass where small rodents dwell. This juvenile female Snowy Owl successfully caught a Meadow Vole (along with a footful of grass) in its talons and proceeded to swallow the vole whole, along with some of the grass. However, most of the grass remained hanging from the owl’s mouth after the vole had been consumed, so it proceeded to grasp the grass with its foot and pull it out of its mouth (yesterday’s Mystery Photo).
Although many people are under the impression that hard weather forces Snowy Owls farther south some winters, the reason for Snowy Owl invasions or irruptions turns out to be linked to either prey population crashes in the north, high productivity breeding years (producing more predators than the prey can support) or a combination of the two. New research has shown that the abundance of Snowy Owls seen in the eastern U.S. during the winter of 2013-14 was the result of a particularly good nesting season on the Arctic tundra. A population boom of lemmings, the Snowy Owl’s primary food source, translated to a population boom of owls.