Susan Benson,
CNHM Director of Education
Could there be anything more perfect than a nuthatch? I sat this morning for a few moments of solitude, in front of the new bird feeder, watching the red-breasted nuthatches visit the sunflower seed feeder. Having it three feet away from my window made for such up-close inspection as I sat, without moving. I watched as it tossed away the seeds to the ground, amazing me with its beauty. I live in the perfect habitat for red-breasted nuthatches, a mixed deciduous-coniferous forest, with mature stands of decaying large trees. I knew these monogamous birds stay paired up throughout the winter. Then, as I watched it eat from further away, I thought of its appropriate name. The common name, nuthatch, comes from the Eurasian Nuthatch's habit of wedging an acorn into a bark crevice and then breaking it open with blows from its bill. The nuthatch family name is Sittidae, and sitte is a Greek word for "birds that peck on the bark of trees." These are just some of the interesting facts about this well-loved bird.
When building their nests, both male and female red-breasted nuthatches excavate a hole that can take up to 18 days to build. They are known to steal the soft lining from other birds’ nests for their own. Then they repeatedly smear pine pitch and insects around the entrance of their nest to sanitize it. To apply the pitch, they use their beak or a piece of bark with the pitch on it as an application tool. The males will place the resin on the outside, and females place it on the inside. It is believed that the pitch and defensive chemicals of the insects keeps out parasites. It might also discourage predators. The birds prevent it from sticking to themselves by diving right through the hole. It is dead or dying aspens that these birds prefer for their excavations because of the soft wood.
In summer, red-breasted nuthatches eat beetles, caterpillars, spiders, ants, and earwigs, and they raise their young on 100% protein. In fall and winter they tend to eat conifer seeds. They will transport cone seeds from a heavily laden conifer and hoard excess food in nearby larders to help them get through winter. They shove the food into bark crevices and cover them with pieces of bark, lichen or pebbles. Red-breasted nuthatches also eat from bird feeders, often choosing the heaviest food item available, jamming it into bark and hammering it open.
Red-breasted nuthatches have interesting behaviors. One of most comical behaviors to watch is the typical nuthatch movement. Red-breasted nuthatches move quickly on trees, zigzagging downward, relying on their backward-pointing toe to grip the trunk. This advantage helps them see insects hiding in crevices that woodpeckers and birds that only move upward on a tree cannot see. Another behavior seen mostly in winter is when red-breasted nuthatches join foraging flocks of chickadees and other small birds. Also, small groups of nuthatches will spend the night together in tree cavities. Finally, when listening, their call is a “yank, yank” that sounds a bit like a high-pitched tin trumpet.
Did you know that due to the weaker feet of a red-breasted nuthatch, they bathe by puffing their wings out during a rain storm? This is just one more fact I couldn’t leave out, so I end with that nature nugget. I can think of no reason that we shouldn’t all be nuts for nuthatches!
For over 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and new exhibit, Our Shared Planet, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about our exhibits and programs. Post your own stories on the Nature Watch blog at cablemuseumnaturewatch.blogspot.com.
Wednesday, January 27, 2010
Thursday, January 21, 2010
Subnivean Temperatures
Nature Watch
By Susan Benson,
CNHM Director of Education
The subnivean space – perhaps it sounds like something out of a science fiction novel, something you might find on a journey to the center of the earth. However, it is not as mystifying as one might think. Quite simply, the subnivean space is the layer between the ground and snowpack. While the snow cover builds up, the ground gives off heat, creating water vapor that condenses and freezes under the bottom layer of snow, creating small spaces at ground level. Many small animals would never survive the winter cold without this space.
The minute a snowflake falls, it begins changing its shape. It can be affected by the internal snowpack characteristics and the external weather conditions. The first deterioration of a snowflake begins as a “destructive” change, in which the snow grains become more rounded. The unequal temperature distribution in the snowpack causes the water molecules to melt, changing the radiating arms of the snowflakes into a rough, spherical ice particle. These ice grains can then connect together, until they are roughly the same size. This metamorphosis occurs more quickly when air temperature is warmer, and is also influenced by wind or the weight of the snow above. It is this destructive metamorphosis that makes building snow shelters so effective.
The snowpack also is exposed to constructive metamorphosis, a process in which the temperature changes from the bottom to top of the snowpack is significantly different. The snow’s upper part is affected by the air temperature, and the lower part is warmed by the ground. Heat is conducted very slowly upward through the snow, affecting the water vapor distribution, and creating a 100% relative humidity in many of the air spaces in the snow. This process causes the ice crystals at the bottom of the snowpack to get continually smaller. Eventually, they form “depth hoar,” brittle, loosely arranged crystals that create easy movement for small mammals as they search for food under the winter snow.
The third factor which affects snow is the “melt metamorphosis”, in which happens when the snowpack is impacted by above freezing temperatures. Surface snow melt percolates down through the snowpack, encounters lower temperatures, and refreezes. As it freezes, it releases heat, bringing the entire snowpack to a more equal temperature. Rain and fog can also cause a similar effect.
Doesn’t the sun’s solar radiation warm the snowpack as well? We all know that spending a day in the snow in bright sunlight is shocking to our eyes, because snow is highly reflective of incoming solar radiation. Perhaps better than a mirror, snow reflects 75-95% of the sunlight hitting its surface. This means that a small amount of solar energy is available to raise the temperature of the snow. However, aging snow, as it accumulates dust, can decrease the sun’s reflection to as low as 45 percent.
It is easy to see that although complex processes occur, the snowpack provides amazing insulation for the winter survival of organisms. How much snow is enough? One theory is that 20 centimeters is a critical depth. The subnivean layer and its temperature and effectiveness for animal survival can also be affected by the type of snowpack metamorphosis that has occurred. By the time the snowpack reaches 40-50 centimeters, the subnivean environment temperature is almost constant.
Most importantly to our animal world, it is as if the snow peels away from the ground, leaving pockets where mice, voles, and shrews spend the winter. Some predators such as weasels live there too. Under that white snow in your yard there is an entire food chain still at work! Next time you are out for a ski, hike, or on a snowmobile trail, look at the edges of the trails to see if you can observe tunnels created by animals living in the snow.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M or on the web at www.cablemuseum.org to learn more about exhibits and programs.
By Susan Benson,
CNHM Director of Education
The subnivean space – perhaps it sounds like something out of a science fiction novel, something you might find on a journey to the center of the earth. However, it is not as mystifying as one might think. Quite simply, the subnivean space is the layer between the ground and snowpack. While the snow cover builds up, the ground gives off heat, creating water vapor that condenses and freezes under the bottom layer of snow, creating small spaces at ground level. Many small animals would never survive the winter cold without this space.
The minute a snowflake falls, it begins changing its shape. It can be affected by the internal snowpack characteristics and the external weather conditions. The first deterioration of a snowflake begins as a “destructive” change, in which the snow grains become more rounded. The unequal temperature distribution in the snowpack causes the water molecules to melt, changing the radiating arms of the snowflakes into a rough, spherical ice particle. These ice grains can then connect together, until they are roughly the same size. This metamorphosis occurs more quickly when air temperature is warmer, and is also influenced by wind or the weight of the snow above. It is this destructive metamorphosis that makes building snow shelters so effective.
The snowpack also is exposed to constructive metamorphosis, a process in which the temperature changes from the bottom to top of the snowpack is significantly different. The snow’s upper part is affected by the air temperature, and the lower part is warmed by the ground. Heat is conducted very slowly upward through the snow, affecting the water vapor distribution, and creating a 100% relative humidity in many of the air spaces in the snow. This process causes the ice crystals at the bottom of the snowpack to get continually smaller. Eventually, they form “depth hoar,” brittle, loosely arranged crystals that create easy movement for small mammals as they search for food under the winter snow.
The third factor which affects snow is the “melt metamorphosis”, in which happens when the snowpack is impacted by above freezing temperatures. Surface snow melt percolates down through the snowpack, encounters lower temperatures, and refreezes. As it freezes, it releases heat, bringing the entire snowpack to a more equal temperature. Rain and fog can also cause a similar effect.
Doesn’t the sun’s solar radiation warm the snowpack as well? We all know that spending a day in the snow in bright sunlight is shocking to our eyes, because snow is highly reflective of incoming solar radiation. Perhaps better than a mirror, snow reflects 75-95% of the sunlight hitting its surface. This means that a small amount of solar energy is available to raise the temperature of the snow. However, aging snow, as it accumulates dust, can decrease the sun’s reflection to as low as 45 percent.
It is easy to see that although complex processes occur, the snowpack provides amazing insulation for the winter survival of organisms. How much snow is enough? One theory is that 20 centimeters is a critical depth. The subnivean layer and its temperature and effectiveness for animal survival can also be affected by the type of snowpack metamorphosis that has occurred. By the time the snowpack reaches 40-50 centimeters, the subnivean environment temperature is almost constant.
Most importantly to our animal world, it is as if the snow peels away from the ground, leaving pockets where mice, voles, and shrews spend the winter. Some predators such as weasels live there too. Under that white snow in your yard there is an entire food chain still at work! Next time you are out for a ski, hike, or on a snowmobile trail, look at the edges of the trails to see if you can observe tunnels created by animals living in the snow.
Nature Watch is brought to you by the Cable Natural History Museum. For 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility in Cable at 13470 County Highway M or on the web at www.cablemuseum.org to learn more about exhibits and programs.
Wednesday, January 13, 2010
Bobcats
By Susan Benson,
CNHM Director of Education
Coming home one night, I spotted yellow eyes in the road ahead. It didn't look like the same color made by white-tailed deer, so I took even closer notice. As I approached, I was excited to see a bobcat. I knew almost immediately what it was as I made those split-second decisions - the animal was about twice the size as a domestic cat, and although I couldn't see its prominent ear tufts, I caught sight of the short 'bobbed' tail that gives these cats their name. How thrilling it was to have visual evidence of these creatures around my home!
The physical attributes of bobcats vary depending on their location. Bobcats in forested northern territories are usually bigger with darker, dense fur while further south they are smaller small and have lighter coloration. Their coat takes on a reddish coloration during the warmer months, and the markings camouflage this amazing carnivore as they hunt through thick underbrush.
Despite their smaller size, bobcats are very successful predators due to their diverse food choices and adaptability. They can take down prey that are eight times their own weight, choosing first from snowshoe hare and cottontail rabbit populations. They also eat squirrels, birds, porcupines, mice, voles, shrews, birds, insects, and reptiles. Less common food sources such as deer, foxes, or skunks are used when other food is scarce. Bobcats rely on stealth, sneaking up to the prey, then using their long hind legs to produce great bursts of speed, reaching nearly thirty miles per hour. When hunting a rabbit, for example, they will often wait until a rabbit approaches within 15-35 feet, and then pounce. Such sneaky hunting tactics!
Bobcats are solitary, and mostly nocturnal, being most active at dawn and dusk. For those who search for their own bobcat discovery, bobcats prefer heavy forested areas, alder thickets or coniferous swamps. It is estimated that an average density of bobcats varies, but is about 1 bobcat every 25 square miles. Males move a distance of up to 2.6 miles per week, while females move about one mile less. They often use roads or game trails to move between food or resting places, especially in deep snow. If you have a bobcat story to share, please email the Museum at info@cablemuseum.org, or post your own stories on the Nature Watch blog at cablemuseumnaturewatch.blogspot.com.
For over 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.
________________________________________
Cable Natural History Museum
PO Box 416
CNHM Director of Education
Coming home one night, I spotted yellow eyes in the road ahead. It didn't look like the same color made by white-tailed deer, so I took even closer notice. As I approached, I was excited to see a bobcat. I knew almost immediately what it was as I made those split-second decisions - the animal was about twice the size as a domestic cat, and although I couldn't see its prominent ear tufts, I caught sight of the short 'bobbed' tail that gives these cats their name. How thrilling it was to have visual evidence of these creatures around my home!
The physical attributes of bobcats vary depending on their location. Bobcats in forested northern territories are usually bigger with darker, dense fur while further south they are smaller small and have lighter coloration. Their coat takes on a reddish coloration during the warmer months, and the markings camouflage this amazing carnivore as they hunt through thick underbrush.
Despite their smaller size, bobcats are very successful predators due to their diverse food choices and adaptability. They can take down prey that are eight times their own weight, choosing first from snowshoe hare and cottontail rabbit populations. They also eat squirrels, birds, porcupines, mice, voles, shrews, birds, insects, and reptiles. Less common food sources such as deer, foxes, or skunks are used when other food is scarce. Bobcats rely on stealth, sneaking up to the prey, then using their long hind legs to produce great bursts of speed, reaching nearly thirty miles per hour. When hunting a rabbit, for example, they will often wait until a rabbit approaches within 15-35 feet, and then pounce. Such sneaky hunting tactics!
Bobcats are solitary, and mostly nocturnal, being most active at dawn and dusk. For those who search for their own bobcat discovery, bobcats prefer heavy forested areas, alder thickets or coniferous swamps. It is estimated that an average density of bobcats varies, but is about 1 bobcat every 25 square miles. Males move a distance of up to 2.6 miles per week, while females move about one mile less. They often use roads or game trails to move between food or resting places, especially in deep snow. If you have a bobcat story to share, please email the Museum at info@cablemuseum.org, or post your own stories on the Nature Watch blog at cablemuseumnaturewatch.blogspot.com.
For over 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.
________________________________________
Cable Natural History Museum
PO Box 416
Thursday, January 7, 2010
Red Squirrels
Nature Watch
By Susan Benson,
CNHM Director of Education
Last week’s observation of two squirrels chasing each other around the tree brought back funny memories of my interactions with this animal. For years I had appreciated these small red critters as they scolded me with their “chuck, chuck” sounds while waving their tail and stomping their feet at me. This appreciation changed a bit when one day, while napping on my couch, I heard a noise in the kitchen. I looked with surprise, and there, on top of my refrigerator, was a red squirrel. That scolding sound took on a new meaning to me as I spent the next half hour trying to encourage this squirrel to leave the house. After a lengthy search, I still could not figure out how this squirrel found entrance to my home. The next day when I returned home from the Museum, I noticed the artwork on the walls all cockeyed – that squirrel had enjoyed another day while I was hard at work, “playing” inside my house. A few days later, I discovered the toilet paper had been unrolled and pulled all over the house by this mischievous squirrel. Its playful antics ended when I discovered its entrance through the dryer vent (clever, aren’t they?) Now I consider myself fortunate to enjoy them outside of the house.
Active mostly at dawn and late afternoon, red squirrels may spend up to eighty percent of their time foraging for food. One of their main food sources is pine seeds. In the fall, “reds” will cut green cones from trees and store them in their piles, or middens, under logs, at the base of trees, or underground. Up to a bushel of food can be stored in one of these piles. They are able to relocate their buried seeds a few inches underground and deep below the snow with their great sense of smell. However, many midden piles are not found, giving red squirrels an important role as a re-forester. Additionally, “reds” may eat up to two-thirds of a pine seed crop in an area each year. They also eat acorns, beechnuts, seeds, berries, birds’ eggs, and fungi. Red squirrels will bite into a sugar maple’s xylem, letting the sap ooze out, to return later when the water has evaporated and the sugar content is higher.
It is around this time of year when breeding for red squirrels begins, which explains the two red squirrels I observed running around the tree for a dizzying amount of time. “Red” makes its nests in a variety of places including hollows in the ground, in tree hollows, logs or crotches in trees.
Boomer, chatterbox, chickaree, and pine squirrel are just some of the names for a red squirrel. Their scientific name is Tamiasciurus hudsonicus. Tamiasciurus is Latin for “the steward who sits in the shadow of his tail,” and hudsonicus relates to Hudson Bay, where this species was first named. It is only the northern two-thirds of Wisconsin that enjoys the “chatter” of this squirrel that prefers coniferous and mixed forests. If you have your own red squirrel story to share, please email the Museum at info@cablemuseum.org, or post your own stories on the Nature Watch blog at cablemuseumnaturewatch.blogspot.com.
For over 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.
By Susan Benson,
CNHM Director of Education
Last week’s observation of two squirrels chasing each other around the tree brought back funny memories of my interactions with this animal. For years I had appreciated these small red critters as they scolded me with their “chuck, chuck” sounds while waving their tail and stomping their feet at me. This appreciation changed a bit when one day, while napping on my couch, I heard a noise in the kitchen. I looked with surprise, and there, on top of my refrigerator, was a red squirrel. That scolding sound took on a new meaning to me as I spent the next half hour trying to encourage this squirrel to leave the house. After a lengthy search, I still could not figure out how this squirrel found entrance to my home. The next day when I returned home from the Museum, I noticed the artwork on the walls all cockeyed – that squirrel had enjoyed another day while I was hard at work, “playing” inside my house. A few days later, I discovered the toilet paper had been unrolled and pulled all over the house by this mischievous squirrel. Its playful antics ended when I discovered its entrance through the dryer vent (clever, aren’t they?) Now I consider myself fortunate to enjoy them outside of the house.
Active mostly at dawn and late afternoon, red squirrels may spend up to eighty percent of their time foraging for food. One of their main food sources is pine seeds. In the fall, “reds” will cut green cones from trees and store them in their piles, or middens, under logs, at the base of trees, or underground. Up to a bushel of food can be stored in one of these piles. They are able to relocate their buried seeds a few inches underground and deep below the snow with their great sense of smell. However, many midden piles are not found, giving red squirrels an important role as a re-forester. Additionally, “reds” may eat up to two-thirds of a pine seed crop in an area each year. They also eat acorns, beechnuts, seeds, berries, birds’ eggs, and fungi. Red squirrels will bite into a sugar maple’s xylem, letting the sap ooze out, to return later when the water has evaporated and the sugar content is higher.
It is around this time of year when breeding for red squirrels begins, which explains the two red squirrels I observed running around the tree for a dizzying amount of time. “Red” makes its nests in a variety of places including hollows in the ground, in tree hollows, logs or crotches in trees.
Boomer, chatterbox, chickaree, and pine squirrel are just some of the names for a red squirrel. Their scientific name is Tamiasciurus hudsonicus. Tamiasciurus is Latin for “the steward who sits in the shadow of his tail,” and hudsonicus relates to Hudson Bay, where this species was first named. It is only the northern two-thirds of Wisconsin that enjoys the “chatter” of this squirrel that prefers coniferous and mixed forests. If you have your own red squirrel story to share, please email the Museum at info@cablemuseum.org, or post your own stories on the Nature Watch blog at cablemuseumnaturewatch.blogspot.com.
For over 40 years, the Museum has served as a guide and mentor to generations of visitors and residents interested in learning to better appreciate and care for the extraordinary natural resources of the region. The Museum invites you to visit its facility and exhibits, the Curiosity Center and Brain Teasers 2, in Cable at 13470 County Highway M. Also find us on the web at www.cablemuseum.org to learn more about exhibits and programs.
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