Nature Watch
December 31, 2008
By Susan Benson,
CNHM Director of Education
This winter, snowy owls are being reported across Wisconsin in Ashland, Appleton, Horicon, Oshkosh, and Milwaukee. As early as the beginning of November, snowy owls were even seen in the Chicago area. Birders everywhere believe that an irruption is on its way to the northwoods and Midwest. It is comical to imagine an eruption of owls, but note that the word is irruption, not eruption. An irruption of owls is a rapid and irregular increase in numbers when there is a correlation to a crash in northern rodent populations. Owls move south out of their Arctic and Canadian homes, appearing across the northern tier of states. Scientists believe that they are forced to move southward in search of more abundant prey as the lemming and vole population declines.
One theory is that the lemming population is high during the snowy owl breeding season, followed by a crash in the late summer or early fall as the lemmings run out of food, driving these larger numbers of snowy owls farther south in search of food. Add to this the fact that other snowy owl food such as ducks, have also retreated south. Finally, the snow and ice get so deep it is more difficult for the owls to find anything to eat.
For some areas, such as the Great Plains, the snowy owl movements are regular, occurring every season in about the same numbers. In the Midwest, the movements are more cyclical, with only a few being observed one year and dozens the next. During an irruption year, some of the owls that make it this far south can be in poor shape, and there are many stories of humans saving and rehabilitating snowy owls.
Ornithologists suggest that snowy owl irruptions occur about once every four years, with bigger ones about every decade. Data in Illinois showed 59 owls during the winter of 1980/81 and 46 owls in the winter season of 1991/92.
As a birder or phenologist, keep your eyes open this winter for snowy owls favorite habitats. In the far northern tundra, they live in wind-swept, open plains. They seek out similar territory in this region – grassy, snow-covered meadows, fields, airports, or beaches. Snowy owls like to perch a little higher than ground level, so can be seen on fence posts or brush piles. If you see one, in the spirit of good birding ethics, please err on the side of caution by giving them plenty of room when viewing or photographing them.
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 http://www.cablemuseum.org/ to learn more about exhibits and programs.
Wednesday, December 31, 2008
Wednesday, December 24, 2008
Animals in Winter
Nature Watch
December 24, 2008
By Susan Benson,CNHM Director of Education
There are worse things than living for days on end with 20 below temperatures, or 40 below windchills. I know it’s difficult to believe, but it’s true. Imagine this instead…
Arctic terns fly 11,000 miles from the north pole all the way to the South Pole.
Deer eat acorns, fungi, and grass in the winter. They browse on basswood, sugar maple, sumac and other trees and shrubs, and they prefer the pencil-sized woody parts of these plants. They also eat 10-12 pounds of this tasty browse per day. I’ll take a hot burger over a basswood stem any day.
Beavers remain active underneath the ice. Back in the fall they were dragging branches of their favorite trees into the water near their lodge. Throughout the winter they swim out their underwater entrance to reach their food cache. Even on the coldest days, their lodge is built so well that it remains at a temperature above 40 degrees Fahrenheit.
Birds just plain shiver in this weather. Continuously. Crows, ravens, chickadees and finches are just a few of the species that shiver consistently.
Many species that are non-colonial during the warmer months will come together and make communal nests during the winter time. Deer mice, meadow voles, and even squirrels are examples. More individuals huddled together create more body heat and also reduces the amount of surface area exposed to the cold.
Honey bees maintain their body temperature through the winter by clustering together in a ball to conserve heat. The bees achieve an average temperature of 64 degrees in the center of the ball and 50 degrees at the perimeter.
Skunks, woodchucks, bats, bears, frogs, turtles, snakes, and other hibernating or dormant animals breathe slowly and lie cold and stiff without eating anything for months.
The wooly bear caterpillar freezes. They produce a substance similar to the ethylene glycol used in automobile antifreeze to protect them from the cold. By midwinter, the amount of glycerol in an insect’s body can amount to 25 percent of its entire body weight.
Whales must migrate as the water freezes so they go to warmer water to have their babies and return with their babies once they have grown.
Finally, if we think we get cold in the winter, we must consider the wood frog. They freeze solid during the winter months. They have no heartbeat. They do not breathe. Their blood does not circulate. Their nerves barely register electrical impulses. Yet their vital organs are not damaged, even after being frozen solid for weeks on end. In the spring, they simply thaw out and hop away to carry on with their day.
So, when we are feeling chilly and tempted to exclaim “I’m freezing,” or “I’m moving south,” both comments I have used in the past few days, remember that there are animals out there that are actually freezing, or dealing with situations I would not trade for anything.
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.
December 24, 2008
By Susan Benson,CNHM Director of Education
There are worse things than living for days on end with 20 below temperatures, or 40 below windchills. I know it’s difficult to believe, but it’s true. Imagine this instead…
Arctic terns fly 11,000 miles from the north pole all the way to the South Pole.
Deer eat acorns, fungi, and grass in the winter. They browse on basswood, sugar maple, sumac and other trees and shrubs, and they prefer the pencil-sized woody parts of these plants. They also eat 10-12 pounds of this tasty browse per day. I’ll take a hot burger over a basswood stem any day.
Beavers remain active underneath the ice. Back in the fall they were dragging branches of their favorite trees into the water near their lodge. Throughout the winter they swim out their underwater entrance to reach their food cache. Even on the coldest days, their lodge is built so well that it remains at a temperature above 40 degrees Fahrenheit.
Birds just plain shiver in this weather. Continuously. Crows, ravens, chickadees and finches are just a few of the species that shiver consistently.
Many species that are non-colonial during the warmer months will come together and make communal nests during the winter time. Deer mice, meadow voles, and even squirrels are examples. More individuals huddled together create more body heat and also reduces the amount of surface area exposed to the cold.
Honey bees maintain their body temperature through the winter by clustering together in a ball to conserve heat. The bees achieve an average temperature of 64 degrees in the center of the ball and 50 degrees at the perimeter.
Skunks, woodchucks, bats, bears, frogs, turtles, snakes, and other hibernating or dormant animals breathe slowly and lie cold and stiff without eating anything for months.
The wooly bear caterpillar freezes. They produce a substance similar to the ethylene glycol used in automobile antifreeze to protect them from the cold. By midwinter, the amount of glycerol in an insect’s body can amount to 25 percent of its entire body weight.
Whales must migrate as the water freezes so they go to warmer water to have their babies and return with their babies once they have grown.
Finally, if we think we get cold in the winter, we must consider the wood frog. They freeze solid during the winter months. They have no heartbeat. They do not breathe. Their blood does not circulate. Their nerves barely register electrical impulses. Yet their vital organs are not damaged, even after being frozen solid for weeks on end. In the spring, they simply thaw out and hop away to carry on with their day.
So, when we are feeling chilly and tempted to exclaim “I’m freezing,” or “I’m moving south,” both comments I have used in the past few days, remember that there are animals out there that are actually freezing, or dealing with situations I would not trade for anything.
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, December 10, 2008
White/Black Fur
Nature Watch
December 10, 2008
By Susan Benson,CNHM Director of Education
If the color black absorbs heat, why is a polar bear white? This is a question a student asked me this week when I was teaching science and outdoor education in an area school. It turns out that dark or black fur isn’t always the warmest fur to have. Energy does come to animals when the sun is shining. This solar radiation penetrates into the fur, some of which is absorbed at the surface, and some all the way to the skin.
Because our winters have less sun, we have less incoming solar radiation, called insolation. Animals living in our region and latitude are exposed to a lower amount of insolation. Black fur absorbs solar radiation well, but even then, much of the energy is redirected back into the environment again, keeping the sun’s heat from reaching the animal’s skin. A contrast to this is white fur, which reflects some sunlight outward, but also reflects the sun down into the fur layer down to the skin. Add to this the thickness of the fur and how those fur pieces lay over each other, this white fur can more successfully warm the skin. Animals that have dark skin with white fur (as do polar bears) increase their ability to absorb heat. How interesting that white fur is not just about camouflage!
How do humans deal with constant exposure to cold? Can we, who live in the northwoods, ever get “used to the cold”? Evidence does show that humans can acclimatize themselves to colder environments, but usually only with prolonged exposures to that cold. Several groups of people have developed very specific adaptations to cold. Inuits, Norwegian fisherman, and Tibetan and Indian yogis have increased circulation and skin temperature in their extremities. Finnish outdoorsmen can have brown fat in strategic locations. Mailmen of Quebec City have lowered blood pressure and heart rates. Antarctic workers have a higher core temperature. Those with yoga training can exhibit a higher cold tolerance.
Sign me up for the next yoga class! And the next time I feel bad about the extra layers of fat around my body, I’ll just think of it as strategically located cold insulators. Whatever it takes, being outdoors, even in the cold, is worth making some adaptations!
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.
December 10, 2008
By Susan Benson,CNHM Director of Education
If the color black absorbs heat, why is a polar bear white? This is a question a student asked me this week when I was teaching science and outdoor education in an area school. It turns out that dark or black fur isn’t always the warmest fur to have. Energy does come to animals when the sun is shining. This solar radiation penetrates into the fur, some of which is absorbed at the surface, and some all the way to the skin.
Because our winters have less sun, we have less incoming solar radiation, called insolation. Animals living in our region and latitude are exposed to a lower amount of insolation. Black fur absorbs solar radiation well, but even then, much of the energy is redirected back into the environment again, keeping the sun’s heat from reaching the animal’s skin. A contrast to this is white fur, which reflects some sunlight outward, but also reflects the sun down into the fur layer down to the skin. Add to this the thickness of the fur and how those fur pieces lay over each other, this white fur can more successfully warm the skin. Animals that have dark skin with white fur (as do polar bears) increase their ability to absorb heat. How interesting that white fur is not just about camouflage!
How do humans deal with constant exposure to cold? Can we, who live in the northwoods, ever get “used to the cold”? Evidence does show that humans can acclimatize themselves to colder environments, but usually only with prolonged exposures to that cold. Several groups of people have developed very specific adaptations to cold. Inuits, Norwegian fisherman, and Tibetan and Indian yogis have increased circulation and skin temperature in their extremities. Finnish outdoorsmen can have brown fat in strategic locations. Mailmen of Quebec City have lowered blood pressure and heart rates. Antarctic workers have a higher core temperature. Those with yoga training can exhibit a higher cold tolerance.
Sign me up for the next yoga class! And the next time I feel bad about the extra layers of fat around my body, I’ll just think of it as strategically located cold insulators. Whatever it takes, being outdoors, even in the cold, is worth making some adaptations!
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.
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