Nature Watch
April 30, 2009
By Susan Benson,
CNHM Director of Education
Robins hopping over lawns in search of food, singing from tree branches and utility wires, or bathing in rain puddles, are all familiar sights to most people. On the evening of April 16, I observed probably forty robins migrating through my yard. Museum staff often asked about robin behavior. “What do robins do for food when snow is on the ground,” is a common question. This week a call came into the Museum from a member asking, “What is happening with the robin in my back yard? It keeps pecking and flying against the windows of my house.” Robins exhibit many interesting behaviors throughout the year that are worth studying when outdoors.
Late winter seems to always bring a snowfall after the robins arrived. Most of us believe that robins must be struggling, but in truth, robins are not earthworm specific birds. In the late winter and early spring, when insects are not available, robins feed on ripe fruits and berries in trees and shrubs. During the breeding season robins will eat earthworms, beetles, snails, spiders, caterpillars, ants, grasshoppers and other ground-dwelling insects.
When breeding, male robins actively defend their territory, which is one-third of an acre up to several acres. If another male intrudes in his territory, he will fly at the trespasser to scare him away. If this doesn’t work, he will dive-bomb the bird, hitting the invader chest to chest. It is this behavior that occurs when a male mistakes his own image in a window for an opponent. Male robins will beat themselves against windows, thinking they are attacking another robin. They might also attack vehicle mirrors for the same reason. Other times, robins may see the reflective nature of a window, and simply fly into it thinking it is safe to do so. Robins are also known to attack red objects, such as socks or other items on a clotheslines, or ornaments or toys in the lawn, again mistaking them for an imposter. This behavior can go on for days or weeks, but usually the birds do not injure themselves seriously. Usually after the romance of the season ends, so do their territorial antics.
If we watch robins long enough in the spring, we might see several other different displays associated with courtship and territorial behavior. Robins will lift their tails when they believe there is danger. The male or female will lower their head and raise their tail to a forty-five degree angle and flick their tail repeatedly while calling out. They drop their wingtips so they are drooping after a dangerous encounter, and sometimes puff their breast feathers out. They also are known to sound their alarm call at a human approach when nesting. Robins will mob nest predators such as crows in areas where there are large numbers of robin nests. When you see a robin perched or flying in midair with a wad of mud or grass in its beak, or a line of mud across the female’s breast, she is nest building. The females work this mud into place with their feet and bill, molding it into that perfectly circular shape with their bodies. When we observe a robin flying off with food in its beak, which is a sign that there are young in a nearby nest. After breeding season is over, we can watch as robins gather for the night in communal roosts, located in trees, under bridges or barns, containing a few to several hundred birds. These are all behaviors worth watching for.
Sometimes we may observe robins “listening,” apparently for their food. It is believed that robins use sight rather than sound for finding food. When tilting their head they are most likely checking the ground with one eye, looking for worms or their castings. Another common thing to look for is when robins thump on the ground with their feet, trying to stimulate movements from the worms before catching them. If we took our shoes and socks off, stamped our feet on the soil a few times, would we be able to feel the movement of worms? What an amazing feat.
Robins have less reproductive success, with up to 80 percent of the young dying each year. Blue jays, ravens, crows, squirrels, chipmunks and raccoons eat robin eggs and nestlings. During the winter they are a favorite food for great horned and barred owls, and hawks and falcons will prey upon the adults in flight. Since they feed on the ground, young and old are exposed to domestic cats. Historically, robins suffered from the insecticide DDT (in the 1950s and 1960s) as they ate earthworms with higher levels of DDT in their bodies.
What can we do to aid robins’ success? Avoid using insecticides. Leave some “forest floor” in open soil by leaving leaf litter to provide for ground foraging. Plant native fruit and berry-producing trees and shrubs. If robins are attacking our car mirrors, place small paper sacks over the mirrors when parked. Where birds are striking windows, break up the window’s reflection by hanging strips of tape, string, or other material six inches apart on the outside of windows. Avoid using commercial silhouettes used to frighten birds, as robins quickly lose their fear of the shapes. Rubbing a bar of soap on the exterior surface of the window with a design that leaves no area six inches or larger uncovered, or cover windows with black netting.
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.
Thursday, April 30, 2009
Thursday, April 16, 2009
Phenology Notes
Nature Watch
April 16, 2009
By Susan Benson,
CNHM Director of Education
Every day a friend, family member, or Museum visitor shares with me some exciting observation they have made related to spring phenology – “I saw my first robin”; “Look, it’s my first tick”; or “The mergansers are back,” are phrases I have been hearing. Phenology continues to provide joy to many people as they study the life cycles of plants and animals as they respond to seasonal changes. There are many events to keep an eye out in the last part of April.
Mid- to late-April brings the peak spring duck migration, and mallard hens begin nesting during the third week of April. Bald eagles begin nesting, and osprey should be migrating back as more open water becomes visible. Our first sandhill cranes and great blue herons can be observed any time now. Other birds to watch for are the eastern phoebe, yellow-bellied sapsucker, barn swallows (I saw my first on April 8,) bluebirds, house wrens, and brown-headed cowbirds. Spring bird migration is probably one of the most-watched phenological events.
Last week was the first mourning cloak butterfly I observed. The ticks are definitely back. We should also be seeing our first earthworms, evidenced by the robin’s avid search through open fields in town. We might even begin seeing our first bumblebees during the last few days of the month. At 40 degrees Fahrenheit, I even spotted my first spider of the season on Sioux Beach on Lake Superior on April 10. It is in April that we can also look forward to seeing our first black flies and getting our first mosquito bite. These are all events to look forward to!
Sometime in April, painted turtles begin emerging, spring peepers begin peeping, and American toads begin to sing. Hog-nosed snakes are also coming out of hibernation. Salamanders begin moving during the first warm, night rain. The phenology of reptiles and amphibians is very dependent upon temperature and moisture conditions, making it more difficult to predict when these animals might emerge. For example, wood frogs will not be present until night temperatures are over 50 degrees Fahrenheit. Many scientists are using amphibian data in current research on the effects of climate change because of their sensitivity to temperature and moisture. It is worth recording annual amphibian information in order to look at general patterns over a longer range of time.
There is much happening in the mammal world in April. Coyote pups and mink kits are born. Black bears leave their dens in mid-April. Little brown bats usually leave hibernation during the third week of April. Snowshoe hares begin turning brown. Raccoon kits are born in a hollow tree, brush pile, or other chosen site.
Plants begin their winter-free growth during April. Trees begin to flower. Bloodroot blooms. The first dandelions begin blooming by the end of the month. It is during this growing season that mature trees can increase their circumference by roughly one inch every year. Spring is a transition, a process that transforms the winter woods with its bare trees to the lush green of May. In the plant world, the process moves step by step, from the forest floor until it finishes with the explosion of growth in the tallest trees.
Each of us uses different phenological sightings as our signs of spring. For me it’s my first mourning cloak butterfly, or the eastern phoebe that visits my home to nest every spring. Please send your observations by Emailing the Museum at info@cablemuseum.org. Please be sure to include information about the observation, date, and location for our records.
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.
April 16, 2009
By Susan Benson,
CNHM Director of Education
Every day a friend, family member, or Museum visitor shares with me some exciting observation they have made related to spring phenology – “I saw my first robin”; “Look, it’s my first tick”; or “The mergansers are back,” are phrases I have been hearing. Phenology continues to provide joy to many people as they study the life cycles of plants and animals as they respond to seasonal changes. There are many events to keep an eye out in the last part of April.
Mid- to late-April brings the peak spring duck migration, and mallard hens begin nesting during the third week of April. Bald eagles begin nesting, and osprey should be migrating back as more open water becomes visible. Our first sandhill cranes and great blue herons can be observed any time now. Other birds to watch for are the eastern phoebe, yellow-bellied sapsucker, barn swallows (I saw my first on April 8,) bluebirds, house wrens, and brown-headed cowbirds. Spring bird migration is probably one of the most-watched phenological events.
Last week was the first mourning cloak butterfly I observed. The ticks are definitely back. We should also be seeing our first earthworms, evidenced by the robin’s avid search through open fields in town. We might even begin seeing our first bumblebees during the last few days of the month. At 40 degrees Fahrenheit, I even spotted my first spider of the season on Sioux Beach on Lake Superior on April 10. It is in April that we can also look forward to seeing our first black flies and getting our first mosquito bite. These are all events to look forward to!
Sometime in April, painted turtles begin emerging, spring peepers begin peeping, and American toads begin to sing. Hog-nosed snakes are also coming out of hibernation. Salamanders begin moving during the first warm, night rain. The phenology of reptiles and amphibians is very dependent upon temperature and moisture conditions, making it more difficult to predict when these animals might emerge. For example, wood frogs will not be present until night temperatures are over 50 degrees Fahrenheit. Many scientists are using amphibian data in current research on the effects of climate change because of their sensitivity to temperature and moisture. It is worth recording annual amphibian information in order to look at general patterns over a longer range of time.
There is much happening in the mammal world in April. Coyote pups and mink kits are born. Black bears leave their dens in mid-April. Little brown bats usually leave hibernation during the third week of April. Snowshoe hares begin turning brown. Raccoon kits are born in a hollow tree, brush pile, or other chosen site.
Plants begin their winter-free growth during April. Trees begin to flower. Bloodroot blooms. The first dandelions begin blooming by the end of the month. It is during this growing season that mature trees can increase their circumference by roughly one inch every year. Spring is a transition, a process that transforms the winter woods with its bare trees to the lush green of May. In the plant world, the process moves step by step, from the forest floor until it finishes with the explosion of growth in the tallest trees.
Each of us uses different phenological sightings as our signs of spring. For me it’s my first mourning cloak butterfly, or the eastern phoebe that visits my home to nest every spring. Please send your observations by Emailing the Museum at info@cablemuseum.org. Please be sure to include information about the observation, date, and location for our records.
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, April 1, 2009
Swan Song
Nature Watch
April 1, 2009
By Susan Benson,CNHM Director of Education
Who can forget the classic tale of the ugly duckling, where a homely little chick grows into a beautiful white swan? That “duckling” in the story was really a mute swan chick passing through its natural brownish phase before turning white.
The mute swan, commonly found along the East Coast and in parts of the Midwest, is the swan typically featured in artwork and folklore as a symbol of grace and beauty. However, many people consider this nonnative bird undesirable in North America because it harasses native waterfowl and can uproot large quantities of aquatic vegetation.
Mute swans were brought to the United States from Eurasia in the 1800s as ornamental additions to estates, parks and zoos. Over the years, many were released or escaped captivity and, by the 1970s, a resident population had established itself in Wisconsin and has been growing ever since.
By contrast, trumpeter swans were almost wiped out during the nineteenth century when they were hunted for their meat and feathers. By 1930, fewer than 100 Trumpeters remained in the United States, but a national effort to save the bird seems to have paid off. In 1989, trumpeter swans were reintroduced to Wisconsin and placed on the state endangered species list, and are now making a slow comeback.
Both the trumpeter and mute swans can be found in marshes, lakes and prairies, and both are about the same size, with a wingspan of up to eight feet and weight of up to 30 pounds. How can you tell the difference?
The mute swan is best identified by its orange bill and prominent black fleshy knob extending from the base of the bill to the forehead. Additionally, mute swans typically hold their necks in an S-curve with the bill pointed downward. Contrary to its name, this
bird is not silent, but utters a variety of calls, including grunts and snorts.
The trumpeter swan, by contrast, has a broad, black bill and holds its neck erect and head upright. True to its name, the trumpeter’s voice sounds like a horn. Trumpeter swans form pair bonds that last their entire lives wherever they spend their winter, and usually arrive on their breeding grounds soon after the ice melt in early spring. Once a pair has spent at least two summers at the same nesting location, they form a strong attachment to that site. When we are fortunate to see them they can be a strong reminder of our own attachments to the north woods.
For anyone looking to observe this beautiful trumpeter swan, a short drive can bring successful results. They can be seen along Pacwawong, part of the Namekagon River wetlands along 63 between Seeley and Cable, or in the wetlands along Mosquito Brook Road. Bring along your binoculars for an exciting view!
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.
April 1, 2009
By Susan Benson,CNHM Director of Education
Who can forget the classic tale of the ugly duckling, where a homely little chick grows into a beautiful white swan? That “duckling” in the story was really a mute swan chick passing through its natural brownish phase before turning white.
The mute swan, commonly found along the East Coast and in parts of the Midwest, is the swan typically featured in artwork and folklore as a symbol of grace and beauty. However, many people consider this nonnative bird undesirable in North America because it harasses native waterfowl and can uproot large quantities of aquatic vegetation.
Mute swans were brought to the United States from Eurasia in the 1800s as ornamental additions to estates, parks and zoos. Over the years, many were released or escaped captivity and, by the 1970s, a resident population had established itself in Wisconsin and has been growing ever since.
By contrast, trumpeter swans were almost wiped out during the nineteenth century when they were hunted for their meat and feathers. By 1930, fewer than 100 Trumpeters remained in the United States, but a national effort to save the bird seems to have paid off. In 1989, trumpeter swans were reintroduced to Wisconsin and placed on the state endangered species list, and are now making a slow comeback.
Both the trumpeter and mute swans can be found in marshes, lakes and prairies, and both are about the same size, with a wingspan of up to eight feet and weight of up to 30 pounds. How can you tell the difference?
The mute swan is best identified by its orange bill and prominent black fleshy knob extending from the base of the bill to the forehead. Additionally, mute swans typically hold their necks in an S-curve with the bill pointed downward. Contrary to its name, this
bird is not silent, but utters a variety of calls, including grunts and snorts.
The trumpeter swan, by contrast, has a broad, black bill and holds its neck erect and head upright. True to its name, the trumpeter’s voice sounds like a horn. Trumpeter swans form pair bonds that last their entire lives wherever they spend their winter, and usually arrive on their breeding grounds soon after the ice melt in early spring. Once a pair has spent at least two summers at the same nesting location, they form a strong attachment to that site. When we are fortunate to see them they can be a strong reminder of our own attachments to the north woods.
For anyone looking to observe this beautiful trumpeter swan, a short drive can bring successful results. They can be seen along Pacwawong, part of the Namekagon River wetlands along 63 between Seeley and Cable, or in the wetlands along Mosquito Brook Road. Bring along your binoculars for an exciting view!
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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