An online resource based on the award-winning nature guide

Archive for October, 2019

Keeping A Dead Leaf Partly Alive

If you look on the ground these days as yellow Trembling and Bigtooth Aspen leaves are falling, you may notice that small splotches of green remain in some of them.  These chlorophyll-laden patches are usually found near the bottom of the midrib of the leaf.  If you open the pocket of tissue at the base of the green section, it’s highly likely you will find a minuscule (2 mm long) translucent caterpillar (a microscope may be necessary to detect it).

The caterpillar (larva) first bores into the stem, or petiole, resulting in a swelling. When it reaches the leaf blade it makes an elongated blotch between the midrib and the first lateral vein. The larva is capable of secreting a chemical which prevents the natural deterioration of the leaf.  As a result, chlorophyll is retained in this area and photosynthesis continues to take place, providing the larva with food.  The leaf-mining larva (Ectoedemia sp.) will pupate over the winter (outside the leaf) and emerge next spring as a very tiny moth which will feed on the honeydew secreted by aphids. (Photo: Mined Bigtooth Aspen, Populus grandidentata, leaf)

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Last of the Yellow-bellied Sapsuckers Migrating

Most of us in northern New England are probably seeing the last of the Yellow-bellied Sapsuckers that nested here this summer.   Unlike most species of woodpeckers (which are year-round residents), a majority of sapsuckers that breed this far north end up migrating further south; southern U.S. and Central America are where most of them overwinter. Females have been observed migrating before males, and spending the winter further south than males.  We don’t often see sapsuckers migrating, as they do so at night and are relatively quiet when flying.  Occasionally you may come upon one during the day resting motionless on a tree, or even briefly drumming.

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Green Stain Fungus Fruiting

Sac fungi, or ascomycetes, are a group of fungi most of which possess sacs, or asci, in which spores are produced. The relatively common blue-green cup fungi, Chlorociboria aeruginascens and its close relative, Chlorociboria aeruginosa, are in this group and are referred to as Green Stain Fungi (as well as Green Elfcup or Green Wood Cup). Most of the time you do not see the actual fruiting bodies of these fungi.  More often you come across the brilliantly blue-green stained wood (often rotting logs of poplar, aspen, ash and oak) for which these fungi are responsible. Woodworkers call this wood “green rot” or “green stain.” 14th and 15th century Italian Renaissance woodworkers used Chlorociboria-infected wood to provide the green colors in their intricate wood inlays. The blue-green discoloration is caused by the production of the pigment xylindein, which may make wood less appealing to termites and has been studied for its cancer-fighting properties.

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Yellowjacket Nests Being Raided

Because yellowjackets do not produce or store honey one might wonder why striped skunks, raccoons and black bears frequently dig up their underground nests.  It is the young yellowjackets (larvae), not honey, that is so highly prized by these insect-eating predators.  At this time of year it is crucial for them, especially black bears who go for months without eating or drinking during hibernation, to consume enough protein to survive the winter.

Whereas adult yellowjackets consume sugary sources of food such as fruit and nectar, larvae feed on insects, meat and fish masticated by the adult workers that feed them. This makes the larvae a highly desirable, protein-rich source of food. (Yellowjacket larvae reciprocate the favor of being fed by secreting a sugary material that the adults eat.)

Three to five thousand adult yellowjackets can inhabit a nest, along with ten to fifteen thousand larvae. Predators take advantage of this by raiding the nests before frost kills both the adults (except for fertilized young queens) and larvae in the fall.  Yellowjackets are most active during the day and return to their underground nest at night.  Thus, animals that raid them at night, such as raccoons, striped skunks and black bears, are usually very successful in obtaining a large meal.  Occasionally, as in this photo, the yellowjackets manage to drive off predators with their stings, leaving their nest intact, but more often than not the nest is destroyed and the inhabitants eaten.  (Thanks to Jody Crosby for photo op of yellowjacket nest (circled in red) dug up by a black bear – note size of rock unearthed.)

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Cottongrass

If you go to a bog at this time of year, you are apt to find a sea of white, cottony balls waving in the breezes.  These are the seed heads of Cottongrass (Eriophorum sp.), which are actually not grasses but sedges. (In contrast to grasses, which have hollow stems, the stems of most sedges are solid and triangular.) The similarity of these heads to cotton gave this plant its common name.

Cottongrass grows in acidic wetlands and bogs.  It tolerates cold weather well, and is found in the northern half of the U. S. as well as further north where it is food for migrating Caribou and Snow Geese on the tundra as well as Grizzly Bears and Ptarmigan.

The cottony seed plumes, which aid in the dispersal of Cottongrass seeds, are too short and brittle to be made into thread, but they have been used for pillow-stuffing, wound dressing and in the production of candle wicks and paper.

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Dust Baths

Some species of birds “bathe” in substances other than water. Often dust or sandy soil is the material of choice, but rotten wood and weed particles are also used.  Dust baths, also called dusting or sand bathing, are part of a bird’s preening and plumage maintenance that keeps feathers in good condition. The dust that is worked into the bird’s feathers while it kicks its feet and beats its wings in the sand will absorb excess oil to help keep the feathers from becoming greasy or matted. The oil-soaked dust is then shed easily as the bird fluffs its feathers and shakes itself vigorously. Usually some feathers come out as well, and it’s often possible to determine what species of bird has taken a bath by the feathers left behind. The pictured dust bath is sprinkled with Wild Turkey feathers.  Ornithologists feel that regular dusting may also help smother or minimize lice, feather mites, and other parasites.

Hundreds of bird species have been recorded as dusters.  Those that take regular dust baths include sparrows, pheasants, turkeys, thrushes, thrashers and wrens.  (Thanks to Jody Crosby for photo op.)

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Last Reminder: 2020 Naturally Curious Calendars Orders Being Taken Until November 10th

 

Orders for the 2020 Naturally Curious Calendar can be placed by writing to me at 134 Densmore Hill Road, Windsor, VT 05089. The calendars are printed on heavy card stock and measure 11” x 17” when hanging. There is one full-page photograph per month. The calendars are $35.00 each (includes postage). Please specify the number of calendars you would like to order, the mailing address to which they should be sent and your email address (so I can easily and quickly confirm your order and contact you if I have any questions). Your check can be made out to Mary Holland.  (For your bank-balancing sanity, checks will be cashed when received, not when calendars are shipped out.)

Guaranteed orders can be placed up until November 10th. Orders placed after this date will be filled as long as my supply of extra calendars lasts. (I have had so many last-minute requests in past years that I have not been able to fill all of the orders placed after November 10th, so if you want to be sure of having your order filled, I encourage you to place your order before that date.)  Calendars will arrive at your door (or wherever you’re having them sent) by mid-December. Thank you so much!

Monthly photographs: January – Screech Owl; February – Bohemian Waxwing; March – Eastern Chipmunk; April – American Bittern; May – Coyote pup; June – Pileated Woodpeckers; July – Painted Turtle; August – Cardinal Flower; September – Fawn/Laurel Sphinx Moth Caterpillar; October –  N.A. River Otter; November –  Downy Rattlesnake Plantain; December – Beavers.


Chlorophyll Breaking Down

It’s as if a magic brush painted the northern New England landscape with every conceivable shade of vibrant red, orange and yellow this past week.  The major player in this phenomenon is chlorophyll, the pigment that gives leaves their green coloration during spring and summer. Chlorophyll is able to absorb from sunlight the energy that is used in transforming carbon dioxide and water to carbohydrates, such as sugars and starch, inside cell-like structures called chloroplasts, a process referred to as photosynthesis. But in the fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process. Chlorophyll breaks down and the green color of leaves disappears, revealing colors that have been masked by the chlorophyll all summer (as well as reds manufactured in the fall).  Imagine a world without chlorophyll, where the bright golds, purples, yellows, oranges and reds of autumn leaves would be the natural colors seen in spring, summer and fall.

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Wolf’s Milk Slime Mold Fruiting

If you examine rotting logs after a rain between the months of June and November, it’s likely you eventually will find what looks like a cluster of tiny (under ¾”), pinkish puffballs growing out of the surface of one or more logs.  Although these growths resemble fungi and were at one time classified as such, they are now classified as slime molds, some of the world’s strangest organisms.  Long mistaken for fungi, slime molds are now classified as a type of amoeba.

The name of these pink balls is Wolf’s Milk Slime Mold, or Toothpaste Slime (Lycogala epipendrum).   They are one of the most frequently noticed slime molds in North America, probably due to the bright color of the young fruiting bodies (aethalia).  The common names derive from the paste-like pink substance found inside of them.  As the fruiting bodies age, both their exterior and interior turn purplish, then gray or brown (see photo inset). At maturity the paste develops into powdery grey spores.

When not fruiting, single celled individuals move about as very small, red amoeba-like organisms called plasmodia.  When certain conditions change, the plasmodia convert into the pinkish, spore-bearing structures seen this this photograph.

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Bumblebees Mating

The adult male bumblebee has only one function in life and that is to mate.  However, research shows that only one out of seven males are successful in this endeavor.  When mating does take place, it is more complex than one might imagine.

In most species, the male bumblebees fly in a circuit depositing a queen-attracting scent (pheromone) from a gland in their head onto vegetation and prominent structures such as trees and rocks.  This usually takes place in the morning, and if it rains, the scent is replaced.  The males then patrol the area, with each species of bee flying at a specific height. Once a (virgin) queen has been attracted, mating takes place on the ground or vegetation, and lasts anywhere from 10 to 80 minutes.  After the male’s sperm has been deposited he inserts a genital plug in the queen which, when hardened, prevents the sperm of other males from entering her for up to three days.  (Photo by Heather Thompson: queen bumblebee with several smaller male suitors)

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Cut-leaved Grape Fern Spores Maturing

There are several species of Grape Ferns in the Northeast, all of which are true ferns, but they are not closely related to the plants we generally think of as ferns. Like other ferns, Grape Ferns do not have flowers; they reproduce with spores, not seeds. A single stalk divides into two blades – one of which is sterile and does the photosynthesizing, and one of which is fertile and bears spores. It is the resemblance of this plant’s clusters of spore-bearing sporangia to miniature clusters of grapes that gives this group of ferns its name.

Cut-leaved Grape Fern, Sceptridium dissectum, is one of the most common species of Grape Ferns in the Northeast. It is often found on disturbed land, is roughly 6” to 8” tall, and has an evergreen sterile frond that appears in July, turns bronze in the fall and dies back in May.  The fertile frond has branched clusters of yellow sporangia containing spores which mature at this time of year.

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Polyphemus Moth Cocoon

Congratulations to Stein, the first person to correctly identify Monday’s Mystery Photo as the cocoon of a Polyphemus Moth!

The Polyphemus Moth is one of our giant silk moths, spinners of the largest cocoons in North America.  Leaves are often woven into the surface of the cocoon in which the Polyphemus pupa spends the winter.  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.

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Mystery Photo

I am often asked how I find the subjects that I photograph.  Sometimes I am consciously looking for specific plants and animals, but more often I’m simply looking for something that is either out of place or out of character.  In this particular instance, I noticed an American Beech sapling with leaves that were bunched up into an odd shape. If you think you know what caused this roughly 2-inch long x 1-inch wide, leaf-covered cylinder, go to the Naturally Curious blog (www.naturallycuriouswithmaryholland.wordpress.com), scroll down to “Comments” and enter your thoughts.  The answer will be revealed Monday, Oct. 7.

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Second Generation of Brown-hooded Owlet Moth Caterpillars Active

In the Northeast, Brown-hooded Owlet moths (Cucullia convexipennis) produce two generations a summer. The larvae of the first generation mature in July, and the second generation matures from late August into October. Brown-hooded Owlet larvae are often found on aster and goldenrod plants, resting on stems (often head down) in plain sight during the day. First generation larvae feed on the leaves and the second generation consumes the flowers of these plants. (Photo: note molted skin above caterpillar.)

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