Nature Watch
By Susan Benson,
CNHM Director of Education
Birds’ nests – can you imagine making a home for your young with a beak? Many might think of a nest as something made by the bird itself, such as the mud and grass nest of the robin, or the more complex woven northern oriole. For some, the nest is simply a spot on the soil, or a knot-hold left by a broken branch, a chamber in a tree, or a mud cavity. A bird’s nest helps hide the parent bird when incubating the eggs and shelters the young. We have evidence that using a nest is critical for warmth, provided by birds near volcanoes or hot water streams lay on heated soil near those places, or by the fact that so many nests are lined with materials that have insulation values. This entire nesting process is truly fascinating.
Why do birds build such elaborate nests? Perhaps, as real estate agents exclaim, is it location, location, location. To get off the forest floor, a bird must build a base that mimics the ground. They need to consider how to keep the eggs warmer, and sine the tops of the eggs are warmer than the bottoms, birds can create a layer of air-trapping insulation between the nest floor and eggs to keep the eggs evenly heated.
Some small birds find protection in the lower parts of nests of larger birds. For example, American kestrels and western kingbirds will often nest in the stick nests of golden eagles, and common grackles and house sparrows will nest in the nests of ospreys. They get protection from the hawk as well as leftover scraps of food.
The nesting habits of birds are varied. Gulls lay eggs on bare ground or rocks. Woodpeckers hew out a deep nest in a rotten limb. The kingfisher digs one out of a sandy bank, while the cuckoo takes possession of the nest of some other bird. The northern oriole constructs a hanging nest of elaborate workmanship. Using thin plant fibers, they loop one around the branch, hold down the irregular spiral, poke a new piece of material into it, pull it through, and loop it around the branch. They sometimes double the new end back, making a knot, by accident. When finished with the exterior weaving, they line the nest, and after ten thousand insertions of material and weeks of effort, they are ready to lay eggs.
The largest nests on record in North America have been built by the bald eagle. One in Vermillion, Ohio had been occupied by eagles for 35 years and was estimated to weigh about two tons when it crashed to the ground. What a nest!
The cup of the nest built by songbirds rests on a foundation nest of twigs interwoven with grasses, weed stems or rootlets, and is lined with finer grasses, mosses, strips of bark, dead leaves, pine needles, feathers, and animal hairs.
Some birds use mud or leaf mold to hold the nest together. Other birds use saliva to cement together the nest materials. Hummingbirds use spider webs to construct their tiny nest. Some birds will use all sorts of man-made products including Kleenex, barbed wire, and strips of plastic.
Saying someone is bird-brained seems like a compliment to me. The effort and innovation that birds have used to design such a wide variation of methods to protect their young suggests a high level of intelligence. Keep your eyes out for birds’ nests and the activities birds do this time of year to care for their young. Please continue to Email any observations to info@cablemuseum.org.
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 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.
Thursday, May 28, 2009
Thursday, May 21, 2009
Warblers, Ovenbirds, Black Throated Warblers
Nature Watch
by Susan Benson,
CNHM Director of Education
"Teacher, Teacher, Teacher!" As a child, many of us may have exclaimed this to
our favorite elementary teachers. Today, it is instead the English translation of
the sound of the ovenbirds. This week we should be hearing this sound in the
forest as this six-inch high warbler returns from its 2,300 mile migration from
Nicaragua. Another sound that should be heard this week is the black-throated
green warbler, singing out to us, "zee-zee-zee-zoo-zee" Although found in two
slightly different habitats, these are both forest-dwelling birds that spend
their summers in northern Wisconsin, and are worth listening for, as we almost
never see them.
Ovenbirds migrate at night, flying 39 miles per hour to reach their northern,
summer home. The term "ovenbird" comes from the shape of their nests, built on
the ground with Pennsylvania sedge that resembles the shape of a Dutch oven.
When we hear the "t-cher" sound, it is the males often singing from near the
ground, and the call gets louder as they sing. Nearby male ovenbirds sing
together. One male begins singing, and the second starts immediately after. They
pause, and then sing one after the other again for up to forty repetitions. The
second joins in so quickly that they may sound as if only one bird is singing.
Ovenbirds hop across the forest floor of Wisconsin's mature forests, preferring
upland deciduous trees, or mixed conifer and deciduous forests. Ovenbirds forage
for insects off leaf litter on the forest floor.
It must be a challenging life being a small, migratory bird. It is believed that
half of all adult ovenbirds die each year. Extensive studies have been made on
ovenbirds in the Chequamegon-Nicolet National Forest on the impacts of forest
fragmentation. In areas where the forests have decreased to very small sizes, egg
predation occurs more frequently. Studies are currently underway in Drummond and
Cable study plots to determine the impacts of exotic earthworms on ovenbirds and
other ground-nesting bird species. Although, not a species of special concern, it
is also believed that the populations are declining in the east as the forest
becomes more mature. With healthy populations in northern Wisconsin, ovenbirds
share a welcome sound to greet other forest dwellers such as ourselves until
early June.
The dark black bib and bright yellow face of the black-throated green warbler is
rarely seen, but the sound is often heard as they sing in coniferous forests. The
males begin their "zee-zee-zee-zoo-zee" in the middle of his territory to attract
females, and later in the breeding season to deter other males. This warbler sings
continuously throughout the breeding season - one individual was heard 466 times
in one hour. These warblers also glean insects from small branches; sometimes
hovering and picking their prey from branches in flight.
The black-throated green warbler is another bird that has challenges in its
summer and winter habitat. They migrate north in the spring from Mexico, where
populations are thought to be declining due to the loss of mature forests. This
species is also susceptible to nest parasitism by the brown-headed cowbird.
When taking a walk outdoors, be sure to be on the look-out for the sights and
sounds of our migratory warblers. Bring your binoculars and bird book, as
warblers are quick to move, and difficult sometimes to identify. Keep a tape or
DVD of bird songs in your vehicle to continue improving your bird song
identification skills. Maybe you'll be lucky enough to spot a "bouquet" or
"confusion" of warblers, which is simply a group of warblers, and is, simply
beautiful to see.
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 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
"Teacher, Teacher, Teacher!" As a child, many of us may have exclaimed this to
our favorite elementary teachers. Today, it is instead the English translation of
the sound of the ovenbirds. This week we should be hearing this sound in the
forest as this six-inch high warbler returns from its 2,300 mile migration from
Nicaragua. Another sound that should be heard this week is the black-throated
green warbler, singing out to us, "zee-zee-zee-zoo-zee" Although found in two
slightly different habitats, these are both forest-dwelling birds that spend
their summers in northern Wisconsin, and are worth listening for, as we almost
never see them.
Ovenbirds migrate at night, flying 39 miles per hour to reach their northern,
summer home. The term "ovenbird" comes from the shape of their nests, built on
the ground with Pennsylvania sedge that resembles the shape of a Dutch oven.
When we hear the "t-cher" sound, it is the males often singing from near the
ground, and the call gets louder as they sing. Nearby male ovenbirds sing
together. One male begins singing, and the second starts immediately after. They
pause, and then sing one after the other again for up to forty repetitions. The
second joins in so quickly that they may sound as if only one bird is singing.
Ovenbirds hop across the forest floor of Wisconsin's mature forests, preferring
upland deciduous trees, or mixed conifer and deciduous forests. Ovenbirds forage
for insects off leaf litter on the forest floor.
It must be a challenging life being a small, migratory bird. It is believed that
half of all adult ovenbirds die each year. Extensive studies have been made on
ovenbirds in the Chequamegon-Nicolet National Forest on the impacts of forest
fragmentation. In areas where the forests have decreased to very small sizes, egg
predation occurs more frequently. Studies are currently underway in Drummond and
Cable study plots to determine the impacts of exotic earthworms on ovenbirds and
other ground-nesting bird species. Although, not a species of special concern, it
is also believed that the populations are declining in the east as the forest
becomes more mature. With healthy populations in northern Wisconsin, ovenbirds
share a welcome sound to greet other forest dwellers such as ourselves until
early June.
The dark black bib and bright yellow face of the black-throated green warbler is
rarely seen, but the sound is often heard as they sing in coniferous forests. The
males begin their "zee-zee-zee-zoo-zee" in the middle of his territory to attract
females, and later in the breeding season to deter other males. This warbler sings
continuously throughout the breeding season - one individual was heard 466 times
in one hour. These warblers also glean insects from small branches; sometimes
hovering and picking their prey from branches in flight.
The black-throated green warbler is another bird that has challenges in its
summer and winter habitat. They migrate north in the spring from Mexico, where
populations are thought to be declining due to the loss of mature forests. This
species is also susceptible to nest parasitism by the brown-headed cowbird.
When taking a walk outdoors, be sure to be on the look-out for the sights and
sounds of our migratory warblers. Bring your binoculars and bird book, as
warblers are quick to move, and difficult sometimes to identify. Keep a tape or
DVD of bird songs in your vehicle to continue improving your bird song
identification skills. Maybe you'll be lucky enough to spot a "bouquet" or
"confusion" of warblers, which is simply a group of warblers, and is, simply
beautiful to see.
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 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.
Thursday, May 14, 2009
Jumping Spiders
Nature Watch
May 14, 2009
By Susan Benson,
CNHM Director of Education
We all know the song “head, shoulders knees and toes, knees and toes.” Well, I sing a different version of this song about insects – “Head, thorax, abdomen, abdomen.” First graders in many of the area schools get to sing and learn about insects when I visit their classrooms in the spring as part of the Museum’s MuseumMobile program. Previously we had studied spiders, so first graders in this region are equipped to identify the differences between arachnids and insects. This week in Drummond, we went outdoors to catch insects or spiders in the school forest. One of the highlights of our explorations included the very “cool” jumping spiders. Jumping spiders are truly amazing spiders for many reasons.
A jumping spider’s family name is Salticidae, whose roots come from the Latin word saltare, to jump or dance. Jumping spiders are daytime hunters. Thought to have the best eyesight of most invertebrates, they are well designed to hunt their prey. Using their keen sight, they run toward their prey, slow down, and then stalk as they get closer. A silk dragline is attached to the ground before they jump so they can move to a safe place afterwards. When jumping, they have a hydraulic-like system – by altering the pressure of their body fluids, they can jump without needing muscular legs. With this technique they can jump from 20-80 times the length of their body. In comparison, I would have to be able to jump 433 feet!
When they are not hunting, jumping spiders maintain woven homes for resting and hibernating that are located under stones, bark, or in leaves. Having no local shopping centers to find their food, they must search anywhere and still be able to return to their home. In lab tests, jumping spiders were presented with prey and artificial branches arranged so that the predator had to walk around the obstacles to get to the prey. The spiders were able to scan the “maze”, move in a pathway around the obstacles, rescan the maze, and find the prey. This experiment showed some evidence of memory or intelligence in a small creature with what we would say is a very tiny brain. Without creating a mental map, how else could the spiders have set out a path away from their prey and still had a successful hunt?
Animals of any shape or size can continue to amaze us. Next time you are out for a walk, step slowly through your lawn, or through a meadow to observe the jumping spiders near your home. Or perhaps while sitting on the ground in the sun, you’ll see one approach, jumping lively or maybe looking at you “curiously” with its keen eyesight. Jumping spiders are just one of the animal species with mind-boggling abilities.
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 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.
May 14, 2009
By Susan Benson,
CNHM Director of Education
We all know the song “head, shoulders knees and toes, knees and toes.” Well, I sing a different version of this song about insects – “Head, thorax, abdomen, abdomen.” First graders in many of the area schools get to sing and learn about insects when I visit their classrooms in the spring as part of the Museum’s MuseumMobile program. Previously we had studied spiders, so first graders in this region are equipped to identify the differences between arachnids and insects. This week in Drummond, we went outdoors to catch insects or spiders in the school forest. One of the highlights of our explorations included the very “cool” jumping spiders. Jumping spiders are truly amazing spiders for many reasons.
A jumping spider’s family name is Salticidae, whose roots come from the Latin word saltare, to jump or dance. Jumping spiders are daytime hunters. Thought to have the best eyesight of most invertebrates, they are well designed to hunt their prey. Using their keen sight, they run toward their prey, slow down, and then stalk as they get closer. A silk dragline is attached to the ground before they jump so they can move to a safe place afterwards. When jumping, they have a hydraulic-like system – by altering the pressure of their body fluids, they can jump without needing muscular legs. With this technique they can jump from 20-80 times the length of their body. In comparison, I would have to be able to jump 433 feet!
When they are not hunting, jumping spiders maintain woven homes for resting and hibernating that are located under stones, bark, or in leaves. Having no local shopping centers to find their food, they must search anywhere and still be able to return to their home. In lab tests, jumping spiders were presented with prey and artificial branches arranged so that the predator had to walk around the obstacles to get to the prey. The spiders were able to scan the “maze”, move in a pathway around the obstacles, rescan the maze, and find the prey. This experiment showed some evidence of memory or intelligence in a small creature with what we would say is a very tiny brain. Without creating a mental map, how else could the spiders have set out a path away from their prey and still had a successful hunt?
Animals of any shape or size can continue to amaze us. Next time you are out for a walk, step slowly through your lawn, or through a meadow to observe the jumping spiders near your home. Or perhaps while sitting on the ground in the sun, you’ll see one approach, jumping lively or maybe looking at you “curiously” with its keen eyesight. Jumping spiders are just one of the animal species with mind-boggling abilities.
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 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.
Thursday, May 7, 2009
Watch for in Early May
Nature Watch
May 7, 2009
By Susan Benson,
CNHM Director of Education
Although April showers didn’t shower much in our region, May flowers appear to still be on their way. For some, May brings the first fish caught, the last frost, the first lawn mowing, and the first swim in a nearby lake or river. Regardless of our interests, spring continues to bring exciting natural events for us to observe. Look high and low for any of the following birds or plants of the north woods.
The first hummingbird is often spotted in the first or second week of May. Northern orioles typically return about the same time, but usually in the second week. Rose-breasted grosbeaks can be seen at the feeders again. Other birds to watch for in the first two weeks of May are the catbirds, wood thrushes, scarlet tanagers, indigo buntings, and wood pewees. Warbler migration also begins early in the month.
There are other bird behaviors to watch for this month. For birds, courtship in May sometimes begins aggressively because of the need to defend territory. Some courtship rituals include singing. Most song is emitted by the male, and is delivered from prominent perches, although some species sing during flight. This song is a way of defending territory against other males and to tell a female of the presence of the male. Some studies suggest that birds sing when aroused by an intrusion of another bird species into their territory, showing aggressive competition between species.
Birds that do not sing in courtship have other means of attracting attention, producing percussive and rhythmic sounds. Woodpeckers drum with the bill on dead limbs and nighthawks dive toward their mate producing a booming sound. Ruffed grouse drum their wings while perched on logs. Many birds preen each other and rub their beaks together as a form of courtship. Others use gifts of food. Birds like the common tern, blue jay, cedar waxwing and others will offer their partners food.
Male birds with the showiest plumage and courtship displays do not help raise their young. They may attract and mate with many females but take no part in nest building, hatching eggs, or rearing the chicks. The females have dull plumage, often mottled brown, so they are camouflaged when sitting on the nest.
In the plant world, many trees are currently flowering. Watch for the red bloom of the maples, or the yellow-green birch and aspen catkins, looking more like a worm than a flower. Hepatica is currently blooming. Marsh marigolds should begin blooming soon. Other plants to begin searching for are the trilliums, violets, and columbine.
The Museum staff is enjoying hearing from readers about their phenological observations, and is adding this information to their database. If you have an observation to share, please email the Museum at info@cablemuseum.org. Enjoy the spring outdoors with a bicycle ride or walk, and be sure to bring a pair of binoculars along!
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.
May 7, 2009
By Susan Benson,
CNHM Director of Education
Although April showers didn’t shower much in our region, May flowers appear to still be on their way. For some, May brings the first fish caught, the last frost, the first lawn mowing, and the first swim in a nearby lake or river. Regardless of our interests, spring continues to bring exciting natural events for us to observe. Look high and low for any of the following birds or plants of the north woods.
The first hummingbird is often spotted in the first or second week of May. Northern orioles typically return about the same time, but usually in the second week. Rose-breasted grosbeaks can be seen at the feeders again. Other birds to watch for in the first two weeks of May are the catbirds, wood thrushes, scarlet tanagers, indigo buntings, and wood pewees. Warbler migration also begins early in the month.
There are other bird behaviors to watch for this month. For birds, courtship in May sometimes begins aggressively because of the need to defend territory. Some courtship rituals include singing. Most song is emitted by the male, and is delivered from prominent perches, although some species sing during flight. This song is a way of defending territory against other males and to tell a female of the presence of the male. Some studies suggest that birds sing when aroused by an intrusion of another bird species into their territory, showing aggressive competition between species.
Birds that do not sing in courtship have other means of attracting attention, producing percussive and rhythmic sounds. Woodpeckers drum with the bill on dead limbs and nighthawks dive toward their mate producing a booming sound. Ruffed grouse drum their wings while perched on logs. Many birds preen each other and rub their beaks together as a form of courtship. Others use gifts of food. Birds like the common tern, blue jay, cedar waxwing and others will offer their partners food.
Male birds with the showiest plumage and courtship displays do not help raise their young. They may attract and mate with many females but take no part in nest building, hatching eggs, or rearing the chicks. The females have dull plumage, often mottled brown, so they are camouflaged when sitting on the nest.
In the plant world, many trees are currently flowering. Watch for the red bloom of the maples, or the yellow-green birch and aspen catkins, looking more like a worm than a flower. Hepatica is currently blooming. Marsh marigolds should begin blooming soon. Other plants to begin searching for are the trilliums, violets, and columbine.
The Museum staff is enjoying hearing from readers about their phenological observations, and is adding this information to their database. If you have an observation to share, please email the Museum at info@cablemuseum.org. Enjoy the spring outdoors with a bicycle ride or walk, and be sure to bring a pair of binoculars along!
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
Facts About Robins
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.
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 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.
Subscribe to:
Posts (Atom)
