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.
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.
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.
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.