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Winter Adaptations

Pectination Growth Started

10-12-17 pectinations 049A5827Every fall Ruffed Grouse (Bonasa umbellus) grow skin-like fringes called pectinations on either side of each toe. They serve as snowshoes, helping grouse stay on top of the snow when walking, as well as cling to icy branches while eating the buds of poplars and other trees in the winter. In the spring grouse shed these adaptive fringes.

Ornithological texts describe these growths as appearing in the fall, but usually do not specify exactly when they develop.  A recent look at a road-killed grouse’s foot (photo) showed that pectinations have begun to develop, but have not completed their growth. The pectinations shown here will double their length by the time snow flies.

 

 


Ruffed Grouse Snow Roosting

 

2-20-17-grouse-bed-028

I recently had an experience while snowshoeing which I have always hoped to have, but which has escaped me during all these years of tromping through the woods. I was following the tracks of a Ruffed Grouse and all of a sudden it exploded out of the snow about two feet in front of me as it left its night time shelter. Now that we have over ten inches of fluffy snow, grouse can dive into the snow and spend the night in their self-made snow roosts. Finding a grouse’s snow roost is a relatively common experience; being startled by a grouse exiting one is not.

Diving head first into the snow, the grouse works its way anywhere from three to ten feet, creating a 4-inch-wide tunnel through the snow before it hollows out a small cavity and settles down for the night in its own little igloo. Up until recently, a hard crust prevented grouse from seeking shelter this winter in this manner. Had temperatures been very cold, many grouse would have suffered and even perished under these conditions. Fortunately, they can now roost in the snow, where temperatures are much warmer (as high as 32°F.), and rarely fall below 20°F. regardless of how cold it gets outside. Not only do these roosts hide the occupants from predators, but they provide an energy savings of 30 percent or more for grouse.

(Photo: Snow roost entrance hole (nearest the bottom of photo) where a grouse dove into the snow, and the exit hole (nearest top of photo), three feet from entrance hole, which a Ruffed Grouse created when it exploded out of its roost. If you look closely at the exit hole, you may be able to detect wing marks.)

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Winter Mouse House

11-14-16-mouse-house2-049a1332One of my very favorite animal signs is the winterized home of a Deer or White-footed Mouse. Most songbirds do not re-use their nests. Once the nestlings have fledged, what doesn’t get recycled directly from the nest by other birds or critters slowly disintegrates from rain and snow. That is, unless an agile mouse discovers it and renovates it first. Deer and White-footed Mice are known for using abandoned nests as larders (see  https://naturallycuriouswithmaryholland.wordpress.com/2013/10/25/mice-preparing-for-winter/) or as homes for the winter. For the latter, a roof is constructed, usually out of milkweed or cattail fluff, but I have even found man-made insulation used as construction material for a roof. (The pictured nest has been well insulated with a roof of cattail fluff.)

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Huddling to Keep Warm

flying squirrel3 IMG_8550Animals which remain active year round in northern New England use different strategies to survive the cold winter temperatures. Lowering metabolism through torpidity (on cold nights black-capped chickadees and other species reduce their body temperature as much as 22 degrees Fahrenheit from their daytime level in a process called regulated hypothermia), shivering, caching food in the fall, puffing out feathers to create insulating pockets of air, excavating tunnels under the snow, seeking protection in cavities – these are just a few of the life-saving techniques used by mammals and birds which neither migrate nor hibernate.

Another strategy which some of these animals use is to huddle together to conserve warmth. Huddling reduces the animal’s surface-area-to-volume ratio, since it turns many small animals into a single big animal. The larger the animal, the smaller the surface-area to volume ratio and the less relative area there is to lose heat.

Bluebirds and flying squirrels are two animals which huddle to keep warm. Eastern bluebirds may huddle together in a tree cavity or hollow log in groups of up to ten. Flying squirrels often huddle together in large communal nests, sometimes with populations numbering over two dozen squirrels, in an effort to keep warm. If this is not sufficient, the squirrels will enter a state of torpor until temperatures return to normal. (Thanks to Susan Parmenter for photo op.)

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Ruffed Grouse Nostril Feathers

12-16-14 ruffed grouse nostrils IMG_2376Ruffed Grouse have adapted to cold winter months in a number of ways, from growing “snowshoe” pectinations on their toes to having their legs covered with fine feathers. Equally effective are the feathers covering a grouse’s nostrils, which are thought to heat cold air as the bird breathes in. (Thanks to Sara and Warren Demont for photo op.)


Millipedes Migrating

11-11-14 millipede IMG_8982We don’t often see millipedes because of their preference for secluded, moist sites where they feed on decaying vegetation and other organic matter. Compost piles, heavily mulched shrub or flower beds, rotting logs, or the soil under logs and stones are likely spots to find these arthropods. Millipedes overwinter as adults, and have been seen migrating in the fall, presumably in search of overwintering sites that will provide them with some protection.

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Big Brown Bats Entering Hibernation

11-7-14  big brown bat IMG_7011Big Brown Bats, one of the most widespread mammals of North America, are one of the last species of bat to be seen flying in the fall. A relatively hardy species, the Big Brown Bat can tolerate conditions that other bats can’t. However, once cold weather arrives in the late fall and the nighttime temperatures dip down into the 30’s, they go into hibernation.

Both the Big Brown Bat and the endangered Little Brown Bat are considered “house bats,” because they are the most common bats found in houses in both summer and winter. During October, November and December, Big Brown Bats seek out caves, buildings and mines in which to hibernate. Some may migrate short distances to find an appropriate location for hibernating, but many find hibernacula close to their summer residence. Individuals often become active for brief periods during the winter months, sometimes even changing hibernation sites. Big Brown Bats can live up to 18-20 years in the wild but, unfortunately, most Big Brown Bats die during their first winter because they did not store enough fat to survive through their entire hibernation period.

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Ruffed Grouse Snow Cave

2-18-14 grouse hole 023When snow depth is over 10” Ruffed Grouse are known to dive into it and often burrow a short distance in order to seek refuge from the wind and the cold as well as from predators, a behavior known as “snow roosting.” Because the grouse flies into the snow leaving no tracks and little scent, predators have difficulty detecting them. The major risk is freezing rain which can form a crust on top of the snow, trapping the grouse. The Ruffed Grouse’s behavior allows it to conserve a great deal of energy, as the temperature inside this roost rarely falls beneath 20°F. This conservation of energy translates into less time spent up in trees eating buds, exposed to hawks and other predators. When morning comes, the grouse usually bursts out of the snow, leaving a hole and wing marks, or, as in this case, shuffles its way to the surface of the snow before taking off. The presence of scat indicates that the left-hand cavity in this photograph is where the bird bedded down and its exit was made to the right. (Thanks to Edith Hoose for photo op.)

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Did you know…

11-20-13 black-capped chickadee IMG_0107Black-capped Chickadees actually refresh their brains once a year. According to Cornell’s Laboratory of Ornithology, every autumn Black-capped Chickadees allow brain neurons containing old information to die, replacing them with new neurons so they can adapt to changes in their social flocks and environment.

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Eastern Red-backed Salamanders Headed for Hibernation

11-20-13  eastern red-backed salamander 120Unless you spend time looking beneath rotting logs or sifting through the leaf litter, you’re not apt to see an Eastern Red-backed Salamander, even though they are prolific in our woods. Studies have found over 1,000 of these salamanders inhabiting one square acre of woodlands. Eastern Red-backed Salamanders are not freeze tolerant so they must spend the winter in locations that don’t freeze if they are to survive. Once the temperature drops to the 30’s and 40’s, they migrate downwards and hibernate in deep leaf litter, under rocks or in rock crevices, and as much as 15 inches under the ground in animal burrows.

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Raccoons Gorging

9-17-13  raccoon vomit, corn 203In New England, Raccoons prepare for winter by eating extra food during the fall. Being omnivores, they eat everything from crayfish and mice to nuts and corn. The latter two items are particularly important, as these high carbohydrate foods allow the Raccoons to put on considerable fat reserves for the cold winter months. According to the Farmer’s Almanac, Raccoons are wasteful when it comes to harvesting corn, because they don’t really like sweet corn all that much. You could fool the Raccoon that deposited this pile on the forest floor adjacent to a Vermont corn field. It gorged on so many ears of corn that it got sick, and there wasn’t a hint of anything but corn kernels that came out of its stomach. (The pile was well over a foot in length.)

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Red Squirrel Gardens in the Woods

6-4-13 sugar maple seedlingsi 036Red and Gray Squirrels remain active year round, and thus, need to have access to food throughout the year. In order for this to happen, seeds and nuts must be stored in the warmer months for consumption during the winter and early spring, when food is much harder to find. While Gray Squirrels tend to bury nuts and seeds individually for this purpose, Red Squirrels often cache numerous seeds (mostly conifers and maples) in one spot, dispersing these caches throughout the woods. During the winter Red Squirrels use their memory (and sometimes their sense of smell) to locate these buried treasures. Inevitably some are overlooked and in many of these cases, the seeds germinate. Finding little patches of multiple seedlings, such as this miniature stand of young Sugar Maples, is a good indication that at least one Red Squirrel overwintered in the vicinity.


White-breasted Nuthatch Winter Roosts

1-7-13 white-breasted nuthatch IMG_4447Birds that remain in New England year round use various strategies to withstand cold winter nights. One such strategy involves choosing a site well-protected from the wind, such as a thick stand of conifers, in which to spend the night. Birds that nest in cavities, such as nuthatches and woodpeckers, often roost in holes as well. White-breasted nuthatches usually roost singly. Occasionally two may share a hole, and as many as 29 have been found in a large tree cavity.


Ruffed Grouse Snow Cave

1-3-12 grouse tunnel IMG_0042When the snow on the ground is 10” or more deep, and the night is very cold, ruffed grouse often seek shelter from the elements by diving into the snow and spending the night there. Sometimes they burrow five or ten feet into the snow, but sometimes, as in this case, they stay pretty much where they landed, perhaps a foot or so deep in the snow bank. This adaptive behavior not only hides them from predators, but serves to insulate the bird, as it rarely goes below 20 degrees F. in the cavity, regardless of how cold the air is. More often than not, the grouse defecates during its stay in the snow (dark matter in photograph). When leaving its snow cave, sometimes a grouse will burst out of the snow as it flies away, but as you can see from the groove in the snow in this photograph, this grouse chose to travel by foot.


Spider Egg Sac

12-10-12 spider egg sac3 IMG_6616As a result of many years of evolution, spiders have developed the use of different silks produced by seven glands for various functions (ballooning, webs, wrapping prey, dragline, egg sac, etc.).  The tubuliform gland is responsible for the large diameter silk fibers used in the construction of egg cases.  Unlike other silk glands, which synthesize protein throughout a spider’s lifetime, the tubuliform gland synthesizes silk for only a short time in a spider’s life, just before eggs are laid.  This silk is synthesized only by female spiders, and is the stiffest type of silk, which makes it a very protective covering for eggs. The pictured overwintering spider eggs had three layers of protection:  bark (the photo is of the underside of a piece of loose bark), an outer silk cocoon covering the egg sac and the egg sac itself – a tough layer of silk covering the eggs. (Reluctantly I opened the sac for the sake of an educational photograph, and did my best to re-wrap the eggs.)


Ruffed Grouse Winter Adaptations

12-8-12 ruffed grouse foot IMG_3524The Ruffed Grouse has both behavioral and physical strategies for dealing with the cold, snow and ice of New England winters.  Three of the physical changes that take place in the fall are evident by looking closely at a grouse’s legs, feet and beak. The feathers on its legs grow thicker and further down towards its feet, to provide better insulation.  Small comb-like growths of skin, called pectinations, develop along either side of each toe.  These increase the surface area of a grouse’s foot, and serve as snowshoes in deep snow.  They also help the grouse cling to icy branches while it quickly snips off poplar and other buds at either end of the day.  And on its beak, feathers expand downward to cover its nostrils, slowing the cold air and giving it a chance to warm up before it is inhaled by the grouse.


A Great Christmas Present!

If you’re looking for a present for someone that will be used year round, year after year, Naturally Curious may just fit the bill.  A relative, a friend, your child’s school teacher – it’s the gift that keeps on giving to both young and old!

One reader wrote, “This is a unique book as far as I know. I have several naturalists’ books covering Vermont and the Northeast, and have seen nothing of this breadth, covered to this depth. So much interesting information about birds, amphibians, mammals, insects, plants. This would be useful to those in the mid-Atlantic, New York, and even wider geographic regions. The author gives a month-by-month look at what’s going on in the natural world, and so much of the information would simply be moved forward or back a month in other regions, but would still be relevant because of the wide overlap of species. Very readable. Couldn’t put it down. I consider myself pretty knowledgeable about the natural world, but there was much that was new to me in this book. I would have loved to have this to use as a text when I was teaching. Suitable for a wide range of ages.”

In a recent email to me a parent wrote, “Naturally Curious is our five year old’s unqualified f-a-v-o-r-I-t-e  book. He spends hours regularly returning to it to study it’s vivid pictures and have us read to him about all the different creatures. It is a ‘must have’ for any family with children living in New England…or for anyone that simply shares a love of the outdoors.”

I am a firm believer in fostering a love of nature in young children – the younger the better — but I admit that when I wrote Naturally Curious, I was writing it with adults in mind. It delights me no end to know that children don’t even need a grown-up middleman to enjoy it!


Beavers Ice-Bumping

Ice is starting to form on ponds, and days are numbered when beavers can be out grooming themselves on land or eating freshly-cut branches.  As long as the ice is thin enough to crack by swimming up under it and bumping their heads against it, they will do so, for soon it will be thick enough to lock them into their pond. Life under the ice is challenging.  At 32 degrees F. a beaver’s resistance to heat loss in water is about 1/8th of that in air at the same temperature. This is due to the fact that its fur is compressed in the water, allowing the insulating air between the hairs to escape — a beaver’s pelt accounts for about 24% of its total insulation in water and body fat is responsible for the rest.  Heat is also retained through a beaver’s tail and hind legs, which serve as heat exchangers.  In the summer, a beaver can lose 25% of its body heat through its tail, but it only loses 2% in winter. Even so, it’s no wonder beavers risk getting a headache in order to see the sun for the last time until spring.


Insects in Winter

What happens to insects this time of year?  A few remain active, such as snow fleas, and some, like monarch butterflies, migrate, but the vast majority of insects overwinter in New England.  The insects that stay here are susceptible to freezing due to the fact that they cannot control the temperature of their body.  Some insects, such as woolly bear caterpillars, can tolerate having ice form in their tissues, but most insects go into a state known as diapause.  When the days start getting shorter, these insects reduce the water content of their body, as water freezes at a high temperature compared to other liquids, and replace it with glycerol, which acts like antifreeze, protecting them from freezing. (Please excuse duplicate post.  I’m testing new posting process.)


Meadow Vole Tunnels

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The melting snow has revealed a labyrinth of vole tunnels, which these little rodents excavate in the snow next to the ground in what is referred to as the subnivean layer.  The tunnels are advantageous in several ways – they provide protection from the wind and cold, and keep the voles hidden from predators.  Voles stay in these tunnels as long as the snow is deep enough, finding food in the form of seeds as they dig through the snow.  Every once in a while you’ll find a dining area (close-up photo) where seeds, in this case, white ash, have been eaten.  If you look closely enough you’ll also see some vole scat.


Winter Survival Strategy of Flying Squirrels

 

During the winter flying squirrels often huddle together in large communal nests, sometimes with populations numbering over two dozen squirrels, in an effort to keep warm.  Two years ago 22 of these nocturnal creatures spent the majority of the winter in my log cabin, doing just that.  Although flying squirrels do not hibernate, if temperatures become too severe the squirrels will enter a state of torpor until temperatures return to normal.


Red Fox Winter Beds

Hard to believe as it may be, red foxes spend most nights curled up in the open air — winter, summer, fall and spring–regardless of the temperature.  Often they sleep in open fields, in an elevated area, where they can keep an eye out for approaching danger.  When making a bed, they curl up in a ball and wrap their bushy tail around themselves, covering their faces.  According to Leonard Lee Rue, when foxes sleep in the open, they usually doze for 15 to 25 seconds and then wake up, look around carefully, and nap again.  Only when a fox sleeps in dense cover does it go into a heavy sleep, waking every hour or so. If you look closely, you can see two fox beds in this photograph — one at about one o’clock and one at about seven  o’clock. Each is about a foot in diameter.


Naturally Curious wins National Outdoor Book Award

I am delighted to be able to tell you that this morning I learned that NATURALLY CURIOUS won the Nature Guidebook category of the 2011 National Outdoor Book Awards.  I’m honored and humbled by this recognition.   http://www.noba-web.org/books11.htm


Ruffed Grouse Winter Adaptation

Every fall ruffed grouse grow skin-like fringes called pectinations on either side of each toe.  They serve as snowshoes, helping grouse stay on top of the snow when walking, and also help them cling to icy branches while eating the buds of poplars and other trees in the winter.  In the spring grouse shed these adaptive fringes.  The bird whose foot is in this photograph met its untimely death about a week ago (they frequently fly into windows, as this one did), and I was curious to see the stage of development of the pectinations at this time of year.  They appear to be about half to two-thirds the size they will attain when fully developed.