An online resource based on the award-winning nature guide

December

Polyphemus Moth Cocoons

12-15-17 polyphemus cocoon2 IMG_4455The 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.

Advertisements

Gray Squirrel Dreys

12-11-17 squirrel drey IMG_9660

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

12-8-17 snowy owl and meadow vole3 049A9802Only 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.

 

.

 


Mystery Photo

12-8-17 mystery photo2 049A9845

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

12-3-17 milkweed IMG_0973Milkweed, 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.


Snapping Turtle Takes Advantage of Opportunity to Breathe Air

12-28-16-snapping-turtle-15622315_1172616449501958_3688331953512399657_nOpportunities to see turtles in winter are extremely limited, but a hole chopped in pond ice recently revealed a Snapping Turtle swimming in the water beneath the ice. According to Jim Andrews, Director of the Vermont Reptile and Amphibian Atlas(http://vtherpatlas.org/ ), most turtles don’t often burrow into the mud during winter. They need to take in dissolved oxygen from the water and there is not much available in the mud. Turtles take in oxygen through the linings of their mouths and sometimes thin-skinned, capillary-rich areas in their cloaca and armpits. Many turtles are just sitting on the bottom of ponds. They may use a rock, log, or maybe some leaves for a little protection from otters or other predators.

If the ice is clear, it is possible to see turtles swimming beneath it. Andrews suggests that the Snapping Turtle in the photograph is likely picking up an oxygen boost by using its lungs for a change. It may be four more months before it gets another breath of fresh air. (Thanks to Jim Andrews for post and Barb and Paul Kivlin of Shoreham, VT for photo.)

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.


Merry Christmas!

12-23-16-final-merry-christmas-post-049a5032

Naturally Curious posts will resume on December 28th!