A Joyous Season To All!
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.
Spinning Ice Discs
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)
Mystery Photo
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.
Polyphemus Moth Cocoons
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.
Avian Evacuation
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.)
Gray Squirrel Dreys
With most deciduous trees having lost their leaves, squirrel nests, or dreys, are more noticeable. Red Squirrels, Eastern Gray Squirrels and Flying Squirrels all build dreys. Those of the Red Squirrel are round, grassy balls, 8” – 10” in diameter. In contrast, Gray Squirrel nests are usually larger and made of sticks and leaves. Flying Squirrel dreys are so high that they are rarely observed.
The dreys most commonly seen are made by Gray Squirrels. Usually 30 or more feet high, these shelters are typically built near the main trunk of the tree, in a crotch where several small branches meet, or on a strong, thick limb. Construction takes place in the summer or early fall, before trees have formed the abcission layers that cause leaves to separate and fall from branches. Therefore, the leaves on a drey’s branches tend to remain for quite some time, forming an effective water-shedding outer layer.
Branches are loosely woven into a foot-wide hollow sphere. The drey is lined with insulating grass, moss, leaves, and shredded bark. Usually there is one entrance/exit hole, facing the trunk (so as to keep rain out). Often squirrels build two dreys, giving themselves another shelter option should one nest be disturbed by a predator or overrun with parasites.
A drey is usually inhabited by one squirrel, but two are known to occupy a single drey in order to keep warm in the winter. Gray Squirrels give birth in late winter and again in the summer. A more protective tree cavity usually serves as a nursery in the winter, and the drey in summer. The average drey is only used for a year or two before it is abandoned.
Snowy Owl Gets Mouthful When Hunting In Tall Grass
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.
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Mystery Photo
Snowy Owls have begun appearing in New England in search of food, giving us the relatively rare opportunity to observe their natural behavior. Do you know what this Snowy Owl is doing? Please click on “Comments” underneath this post on my blog to respond.
A Win-Win for Milkweed & Monarchs
Milkweed, a perennial plant that can adapt to adverse soil conditions, has recently been recognized as a viable source of fiber for fill for jackets and comforters. Winter coats insulated with a compressed layer of milkweed fluff are have been shown to be as effective at retaining body heat as those filled with down or polyester, and a Canadian company is now manufacturing and selling them.
Although historically considered a “weed,” milkweed came into its own during World War II, when overseas supplies of the insulating fiber from the kapok tree were cut off and milkweed fluff was harvested for use in life jackets. The U.S. government launched a program that enlisted the help of children: if they could fill up a large onion bag of milkweed fluff, they would receive fifteen cents. This incentive proved very popular, and the U.S. was able to stuff over 1.2 million life vests with milkweed fluff. However, after the war, the rising use of synthetics lessened interest in all natural fibers, and milkweed went back to being considered a less than desirable weed.
Recently milkweed populations have been declining, in part due to herbicides and loss of habitat. However, with the growing interest in this plant as a source of commercial fiber it is now being planted as an agricultural crop, with some Vermont and Canadian farmers devoting acres of farmland to its growth. This, of course, is a boon to monarchs, as milkweed leaves are the sole source of food for monarch larvae. Not only is milkweed being cultivated, but the farmers growing it are making an effort not to harvest the plants until monarchs have migrated in the fall. A win-win situation for all concerned.
A Vagrant Brant
Brants are small geese that travel long distances (up to 3,000 miles) several thousand feet up in the air between their Arctic breeding grounds and their coastal wintering grounds. No other species of goose nests as far north, and few migrate as far. The subspecies that overwinters off the middle of the East Coast, the Atlantic or Pale-bellied Brant, typically migrates from northern Canada to James Bay, where it remains for several weeks building up fat reserves. From there most birds fly nonstop to their wintering grounds in Jamaica Bay and other nearby estuaries of greater NYC and New Jersey, arriving in late October and early November.
Occasionally migrating birds, often juveniles, veer a bit off course (often due to weather-related causes) and end up where they don’t belong. Brants are common winter residents in coastal areas during the winter, but are not often seen far from salt water. This fall a lone juvenile vagrant Pale-bellied Brant appeared one day on the shore of a lake in central Vermont, giving inlanders the opportunity to view a Brant up close. While adult birds have a very sophisticated mechanism for plotting their migration from one point to another and for getting back on course if they are displaced because of weather, first-year birds often lack this skill.
Had this Brant been blown off course in this manner 75 years ago, there would have been concern for its survival, as Brants used to feed almost exclusively on intertidal seagrass during the non-breeding season. However, in the 1930’s a disease devastated eelgrass and consequently the Brant population dropped. Brants that survived adapted to an alternative diet which included sea lettuce, saltmarsh grass and lawn grass, making it possible for a 21st century Brant to exist just fine in the interior of New England, at least long enough to refuel before continuing on its way.
Naturally Curious with Mary Holland 
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