Displaying items by tag: american

American Robin

10 April 2010
Published in Birds

Originally published on www.critters360.com

The American Robin is the best-known thrush in North America.  It has adapted to human habitation more than other thrushes, and is seen in almost any city park or suburban lawn.  But before discussing the robin in detail, here is a brief review of the other thrushes in North America.

Family Turdidae

Thrushes are known throughout the world except for the Polar Regions and Polynesia. There are about 304 species in this family worldwide, and 10 in eastern North America.  Many of these are largely birds of the far north, including the varied thrush, the northern wheatear, and the gray- cheeked thrush.

The eastern bluebird lives in much of the U.S. east of the Rockies.  It has a red breast like the robin, but blue back and wings.  Its counterpart in the west is the mountain bluebird, a truly blue bird.

The veery, Swainson’s thrush, and hermit thrush, all with ethereal songs, are found in northeastern woodlands.  The wood thrush is found in most of the U.S. east of the Mississippi except south Florida.

Turdus migratorious or American Robin

The most well known thrush in North America is the Turdus migratorious. It is a common in woodlands, and suburban and urban yards across most of the continent.  Though it migrates, many remain in the snowy north over the winter.  In parts of the south central U.S. and Florida the robin is a winter resident only.

This 10-inch bird is easily recognized with its bright orange-red breast. The bill is yellow, the head nearly black, and the back and wings a grayish-brown.  The throat is white with black striping, and it has a broken white eye-ring.  White spots on its tail are seen as it flies away with its 12 to 14 inch wingspan.

It is first seen in March eating worms on lawns and golf courses.  The jerky, short hopping run is interrupted by brief pauses, and then it hops away again.  In the spring, worms are a major food.  As spring progresses into summer, robins consume large numbers of insects, especially beetles in spring and fall, and grasshoppers in late summer.  They enjoy a wide variety of wild fruit, including berries of barberry, chokecherry, and sumac.  These wild berries are often the only source of food in the winter.  They do eat some agricultural fruit, especially cherries.

Nesting and Breeding

Robins are usually monogamous and nest on a territory as small as a third of an acre.  They are territorial and strongly defensive of their territory and young.  The nest is cup shaped, made mostly of mud and grasses, held together by finer grasses and animal fur.  It is usually in protected evergreens, cedar hedges being commonly used.  Nests are usually less than ten feet from the ground. 

The 3 to 7 eggs are a greenish to turquoise blue, sometimes flecked with brown.  Incubation is mostly by the female for nearly 2 weeks. The young are helpless at first, or altricial.  They are brooded by the female for 14 to 16 days prior to fledging.   The male sometimes helps in this as the female may be starting another nest for a second brood. There are often three broods in the south, 1 or 2 in the north. 

Song and Call

The piercing tremolo of the robin’s song is often the last bird-call heard at night as it roosts shortly after sunset.  In spring and early summer, it is also the first bird heard in the morning.  It’s sometimes loud “cheer-up, cheerily, cheerily, cheer-up” song is a natural alarm clock, rousing one from a sound sleep as early as 3:30 am, well before sunrise. 

Its calls are a more rapid “tut-tut-tut.”  At times this is rather quiet as it is just hopping along in a lawn or park, but it can be very loud as a warning when it perceives a threat, such as from a cat.

Attracting Robins

Especially in the northern snow country of New York or New England, one can entice robins with various berry producing plants like currents, American or Japanese barberry, chokecherries, and Russian mulberry.  Having robins in the garden is beneficial in controlling beetles and grasshoppers. 

By mid-July the robins’ morning song is decreased in intensity and duration, and by August they are usually silent.  From early October, in the city or suburb, you may not see them for the rest of the winter.  This is because they move to mixed trees and shrubs that offer more protection and food sources of wild berries.  Whether they are seen or not over the winter, one is sure to welcome their song next March as the harbinger of spring. 

Sources:

Alsop, Fred J. III.  Smithsonian Handbooks: Birds of North America, New York:  DK Publishing, 2001.

Gilliard, E. Thomas.  Living Birds of the world, Doubleday, Garden City, NY: 1958

Mahnken, Jan.  The Backyard Bird-Lovers Guide, Storey Communications, 1998 ISBN 0-87596-804-X

Pearson, T. Gilbert, Editor.  Birds of America, 1936, Doubleday & Company.

Peterson, Roger Tory.  A Field Guide to the Birds, 1980.  (Eastern North America)

Web Sources

The Great American Bird Count:  Map of Robins in North America, February 2010

American Crow

09 April 2010
Published in Birds

Originally published on www.critters360.com

Crows are nearly universally known, except for in parts of the South Pacific and southern South America.  The general behavior and habits of the American crow would be well known to those who observe the jackdaw in Eurasia and North Africa.

While they might be observing different varieties of crows, there are many stories about the crow’s intelligence and cunning on both sides of the Atlantic.  From Eurasia, perhaps the best-known stories are from Aesop’s Fables.

Crows are members of the Family Corvidae, which has about 100 species worldwide.  The crows in North America include the fish crow, the American Crow, and the white- necked and northern ravens.  The large family also includes the blue jay, scrub jay, gray jay, and black-billed magpie.

The American Crow

The Corvus brachyrhynchos is the most widespread and well-known bird in North America.  The American crow is about 17-21 inches long with a wingspan of 33 to 40 inches. It is all black, and its distinctive “caw-caw-caw,” with its many variations, is a common sound in city or country. 

With intelligence and social behavior, including sentries, crows are difficult to approach.  When flying in a flock, they are usually far apart rather than in a tight formation.  Crows form large flocks, especially in winter.  Up to several thousand birds may fill the entire horizon.

Crows eat nearly anything, from insects to seeds and sprouting plants, eggs and young of birds and reptiles, small mammals, garbage, and carrion   They are often seen on the ground in dumps, behind super markets, or at the roadside eating carrion, oblivious to passing traffic. While single birds may be seen in the country, in cities, they are most often seen in groups of 5 to 10 birds, or larger flocks.

Breeding and Nesting

American crows are monogamous and solitary nesters.   The nest is made of twigs and branches, lined with grass, feathers, bark, moss, leaves, and hair.   This is usually in the fork of a tree, often over 50 feet off the ground. 

The 4 to 8 eggs are pale bluish-green to pale olive-green with brown or olive gray splotches.  Incubation is about 18 days by both sexes.  The altricial young spend about a month in the nest before fledging.  There may be two broods in the south.  

Crow Behavior

Crows are an interesting bird to watch for behavior that can sometimes be quite surprising.  They will sometimes “mob” a hawk or owl, seen as a threat.  Several crows may dive-bomb a hawk from above, forcing it into the tree-tops. 

As they often eat eggs and young birds, they are a threat to many smaller birds. Sometimes the crow is on the receiving end of mobbing behavior as a response.  This is commonly done by grackles and red-winged blackbirds.  As the crow flies through an area, it is harassed and attacked, usually from above and behind.  The smaller birds pester the crow unmercifully to drive him out of the neighborhood.

At other times, a crow may actually try to attack small animals imitating a raptor.  One day, my wife and I observed a crow chasing a squirrel.  It was trying to clutch the frightened animal with its feet, similar to a hawk swooping down on a rabbit or mouse.  Its feet are not effectively strong like a raptor’s talons; it was unsuccessful in catching the squirrel.   It certainly was comical, though it’s doubtful if the harassed squirrel appreciated the joke.

But the crow is sometimes on the receiving end of this joke as well.  Crows will often be in groups with a sentry bird, and one cawing crow may soon lead to a chorus when a threat is near.  One April morning near dawn in a park’s woodlands, there was a tremendous outcry of several crows that just would not stop.  This small flock of crows was in frenzy, in trees about 20 to 30 feet off the ground.  At the base of a tree, there was a crow struggling on the ground, its head and upper torso disappearing down the throat of a red fox. 

The fox also out witted the crow in Aesop’s fable of the Fox and the Crow.  In that story, the fox flattered the crow into speaking to prove it had a voice matching its beauty.  As the crow cawed, it dropped a piece of stolen meat, which was then eaten by the fox. 

In the spring morning observation related above, the fox again outwitted the crow.  This time it resulted in the crow’s demise amidst the lamenting chorus of its friends and family.

Sources

Alsop, Fred J. III.  Smithsonian Handbooks: Birds of North America, New York:  DK Publishing, 2001.

Gillard, E. Thomas.  Living Birds of the World.   Doubleday & Company, Garden City, New York:  1967.

Pearson, T. Gilbert, Editor.  Birds of America, 1936, Doubleday & Company.

Peterson, Roger Tory.  A Field Guide to the Birds, 1980.  (Eastern North America)

Web Sources

Aesop’s Fables.com  The Fox and the Crow.

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