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Archive for November, 2021

Blue Feathers

The colors in the feathers of a bird are formed in two different ways, from either pigments or from light refraction caused by the structure of the feather. Red and yellow feathers get their color from actual pigments (carotenoids) that come from the bird’s diet. Blue, however, is a structural color, created by the way light waves interact with the feathers and their arrangement of protein molecules, called keratin.

Thus, no birds have blue feathers made from pigments – they are blue strictly from the structure of the feathers.  Different keratin structures reflect light in subtly different ways to produce different shades of what our eyes perceive as the color blue.

If you observe the blue feather of an Eastern Bluebird, Blue Jay or Indigo Bunting in normal lighting conditions you will see the expected blue color. However, if the feather is back-lit, and the light is transmitted through the feather, it will look brown. The blues are lost because the light is no longer being reflected back and the brown shows up because of the melanin in the feathers.

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Witches’ Brooms

If you’ve ever seen a tree or shrub that looks like its growth has gone haywire in one particular spot, you may have come across a phenomenon called Witches’ Broom.  Witches’ Broom is defined as an “abnormal brush-like cluster of dwarfed, weak shoots arising at or near the same point.” This deformed mass of twigs and branches occurs in response to pathogens and insect pests (mites, aphids, nematodes, fungi, viruses, bacteria and phytoplasmas (parasitical bacteria)) as well as stressful environmental conditions.

Susceptible plants include alder, serviceberry, birch, cherry, elm, fir, hackberry, honey locust, juniper, red cedar, mulberry, oak, ash, willow and spruce, among others. Often Witches’ Brooms are relatively small — a foot or so in diameter. The one pictured required multiple years of growth to reach its current size.  Most Witches’ Brooms are not fatal, just disfiguring.

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Snow Geese Migrating

The Snow Goose (Anser caerulescens) is one of the most abundant species of waterfowl in the world.  The eastern population of Snow Geese migrate in very large flocks from their high Arctic breeding grounds to their wintering grounds along the Atlantic coast during October and November. Birds from the same breeding population use many of the same stopover sites, or staging areas, where they rest and refuel each year. Here they forage and eat the stems, seeds, leaves, tubers and roots of grasses, sedges and rushes in addition to waste grains such as wheat and corn in fields where crops have been cut.

 Snow Geese are dimorphic – they have two color morphs, light-morph (white) and dark-morph (blue).  Most of the blue-morph Snow Geese breed and winter in central U.S., however, they are present in the East, just not as common as the white-morph. Until 1983, the 2 color morphs were considered separate species.

Those of us lucky enough to live near a staging area keep our eyes out for clouds of white “snowflakes” swirling in the sky at this time of year, and our ears tuned for the sound of baying hounds, for that is what an approaching flock of thousands of Snow Geese sounds like. (Photo: Blue-morph Snow Geese circled in red.)

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Spider Egg Sacs

Spiders spin different kinds of silk for many different purposes. There is both sticky and non-sticky silk used in webs (the spider walks on the non-sticky), silk for wrapping up prey, silk for dispersing themselves in the wind, silk used as a safety drag line and silk used for egg sacs.

The egg sacs of different species of spiders are quite distinct, so much so that sometimes you can identify the species of spider that spun the sac.  They may be built inside a burrow, under loose bark, in a web, in a curled leaf, suspended on a long line, or in a rock crevice. While some spiders abandon their egg sac, some stay with it, guarding it until spiderlings emerge.  Others may carry their egg sac about with them in their jaws or spinnerets until hatching occurs.

The egg sac silk protects the eggs against physical damage and excessive drying, wetting or heating, as well as providing a shield against predators like ants and birds. The average female spider’s egg sac holds about 100 eggs, but some large spiders can produce a sac that holds 2,000 eggs.

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Rough-legged Hawks Returning

It’s time to keep an eye out for Rough-legged Hawks (Buteo lagopus) which are currently migrating south from their breeding grounds on the arctic tundra to spend the winter in northern states. They look for habitat similar to the open habitat they left – agricultural fields, meadows, and airports fit the bill well.  In Vermont, the Champlain Valley is a known winter destination. You see them on the ground, perched on fence posts, telephone poles and tree tops, as well as hovering in the air as they forage for small rodents below.

As to their common name, the “rough-legged” refers to the feathers that grow down their legs to the base of their toes, a clever adaptation for the cold climates they inhabit. Rough-legged Hawks come in two color morphs, light and dark.  North America is the only place where the dark morph is found, and it is more common in the East than the light morph.  The dark belly of the light morph Rough-legged Hawk pictured indicates that it is a female.

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Oak Apple Galls

Galls are abnormal plant growths that are caused primarily by insects, but also by fungi, mites, nematodes and bacteria.  Each gall insect has a specific plant host which produces a distinctive-looking gall. Of the 2,000 gall-producing insects in the United States, 1,500 of them are gall wasps or gall gnats. Of the over 800 different gall-makers on oaks, over 700 are gall wasps.

The pictured golf ball-size gall is referred to as an oak apple gall, specifically the Larger Empty Oak Apple Gall. (There are over 50 species of gall wasps that are known to produce oak apple galls in North America.) This particular gall is called “empty” due to the fact that the inner fibers disintegrate with age, leaving much of the interior empty. It housed the larva of a tiny gall wasp (Amphibolips quercusinanis) through the summer.  An adult gall wasp laid an egg in a growing part of the plant (in this case a leaf bud) in the spring.  The oak reacted to either a chemical secretion, the egg or the burrowing of the hatched larva (it is not known which of these agents is responsible) by forming a growth around it.  This growth, or gall, provided the wasp larva with both shelter and food as the larva developed in a tiny chamber in the center of the gall.  As the larva fed on the nutritious tissue in the walls of the chamber, it (the tissue) was constantly replenished by the oak tree. Eventually the larva pupated and the adult wasp, having emerged from its pupal case within the gall, chewed the tiny round exit hole you see in the gall before flying off to seek a mate.

As with the vast majority of plant galls, oak apple galls cause little harm to the overall health of their oak hosts.

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Calendar Ordering Deadline Reminder

The deadline for ordering Naturally Curious calendars is November 10. (A quick email to to let me know your order is in the mail would be helpful.) In past years, many orders have come in too late to fill, as I need to have them printed in time to get them to you by the holidays for those who give them as gifts. Thank you to those who have ordered calendars this year and in so doing supported my work.

Ordering information: You can order calendars by writing to me at 505 Wake Robin Drive, Shelburne, VT  05482. 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 contact you if I have any questions). Your check can be made out to Mary Holland.

Hidden Treasures Under Rotting Logs

Eight out of ten logs that I lifted up (and replaced in the position I found them) this week had tiny pearl-like eggs in clusters about one inch in diameter underneath them.  Roughly 30 eggs were in each cluster. Whether these were slug or snail eggs I could not say, but mature slugs do deposit their eggs in the fall, often after mid-October, so one might assume these eggs were deposited by slugs.  To see the hatching of slug eggs, which can take place in just a few weeks if conditions are right, go to

 If a reader knows categorically how to distinguish snail from slug eggs, please enlighten those of us who are naturally curious with a comment!

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Porcupines Mating

It’s doubtful that there is a female human that would want to change places with a female porcupine.  She (female porcupine) may only copulate once a year.  When that momentous occasion occurs, she is sprayed by her mate with urine from head to toe as part of the mating process.  And finally, she spends 11 months a year, every year, either pregnant or lactating. 

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Beavers Actively Winterizing Lodges

There are two noticeable differences in the appearance of an active beaver lodge in the fall as opposed to the summer.  One is the presence of a growing pile of freshly-cut branches adjacent to the lodge.  These branches provide resident beavers with the nutrition they will need during the winter months when herbaceous plants are neither available nor accessible.

The second change noticeable in a fall lodge is the presence of massive amounts of mud.  Branches are often placed on top of this layer of mud, so you have to observe the lodge before that happens in order to see the extent of the mud layer.  It provides protection from harsh winter winds which would significantly lower the temperature inside the lodge.  Together, a blanket of snow and a layer of mud serve as excellent insulation for beavers living in the lodge.

In the Northeast, where the temperature often dips into the single digits or lower in the winter, the interior of an active beaver lodge maintains a relatively stable 33° F. – 35° F., roughly the temperature of the water, thanks to the ingenuity of these rodent architects.

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