Tuesday, February 26, 2013

California Condor


California Condor

 
Gymnogyps californianus


Photo: California condor in tree
Sacred to Native Americans and the largest birds in North America, the California condor teeters on the brink of extinction, saved only by captive breeding programs.
Photograph courtesy Scott Frier/U.S. Fish and Wildlife Service
The California condor is the largest flying bird in North America. Their wings may stretch nearly 10 feet (3 meters) from tip to tip. When in flight, these huge birds glide on air currents to soar as high as a dizzying 15,000 feet (4,600 meters).
Like other vultures, condors are scavengers that feast on the carcasses of large mammals, such as cattle and deer. When a big meal is available, the birds may gorge themselves so much that they must rest for several hours before flying again.
Condors were sacred birds to the Native Americans who lived in the open spaces of western America. Today, they are best known as the subjects of a famous captive breeding program that may save them from extinction.
After decades of decline, condors neared the point of extinction in the late 1970s, when only two or three dozen birds survived. No one is sure exactly what cause or causes contributed most to this decline. Many birds died from poison ingestion and illegal egg collection, and all felt the steady loss of the open lands over which they once soared. Fossil records also show that the birds occupied only a fraction of their former range when Europeans first reached America—perhaps because of the loss of the great prehistoric herds that formerly roamed the continent.
California condors mature and reproduce slowly. They don't breed until they are between six and eight years old, and the female lays only one egg every two years. If that egg is removed, however, she will lay a second or a third. With this in mind, scientists began to collect eggs for captive incubation. They also captured wild birds for captive breeding and, when the wild population dropped below 10 individuals, all of the remaining wild condors were brought into captivity in 1987.
Read full here... http://animals.nationalgeographic.com/animals/birds/california-condor/


Sunday, February 24, 2013

Snow Goose


Snow Goose

 
Anser caerulescens


Photo: Snow geese in water
Its numbers in dangerous decline in the early 20th century, the snow goose has made a stellar recovery, so much so that it has overrun its habitat.
Photograph courtesy Dave Menke/U.S. Fish and Wildlife Service
Snow geese are known for their white plumage, but many of them are actually darker, gray-brown birds known as blue geese. These birds were once though to be two separate species, but they have recently been found to be merely two different color morphs of the same bird. A single gene controls the color difference.
Snow geese are harbingers of the changing seasons. They fly south for the winter in huge, honking flocks that may appear as a "U" formation or simply as a large "snowstorm" of white birds. They spend the colder seasons in southern coastal marshes, bays, wet grasslands, and fields. Their diet is entirely vegetarian, consisting of grasses and grains, grazed from damp soils or even shallow water.
At winter's end, snow geese fly north to their breeding grounds on the Arctic tundra. Pairs mate for life, and produce two to six eggs each year in a shallow ground nest. Chicks can swim and eat on their own within 24 hours, but families remain together through the young's first winter. Families can be identified as groups during both the southern and northern migrations.
Read full here... http://animals.nationalgeographic.com/animals/birds/snow-goose/


Monday, February 4, 2013

Sandhill Crane


Sandhill Crane

 
Grus canadensis


Photo: Sandhill crane in flight
Most sandhill cranes live in freshwater wetlands, feeding on plants, grains, mice, snakes, insects, and worms.
Photograph by Marc Moritsch
Sandhills are the most common of all the world's cranes. A fossil from the Miocene Epoch, some ten million years ago, was found to be structurally the same as the modern sandhill crane. Today, these large birds are found predominately in North America. They range south to Mexico and Cuba, and as far west as Siberia.
Migratory subspecies of sandhill cranes breed in the Northern U.S., Canada, Alaska, and Siberia. Each winter they undertake long southern journeys to wintering grounds in Florida, Texas, Utah, Mexico, and California. En route, more than three-fourths of all sandhill cranes use migratory staging areas in a single 75-mile (120-kilometer) stretch along Nebraska's Platte River.
Most sandhill cranes live in freshwater wetlands. They are opportunistic eaters that enjoy plants, grains, mice, snakes, insects, or worms. They often dig in the soil for tubers and can sometimes cause significant crop damage, which brings them into conflict with farmers.
The birds are naturally gray and their heads are topped with a crimson crown. Some cranes preen themselves by adding mud to their feathers and thus taking on a temporary brown hue. This may happen because the birds use their bills to probe for food in muddy wetland soil.
During mating, pairs vocalize in a behavior known as "unison calling." They throw their heads back and unleash a passionate duet—an extended litany of coordinated song. Cranes also dance, run, leap high in the air and otherwise cavort around—not only during mating but all year long.
Read full here... http://animals.nationalgeographic.com/animals/birds/sandhill-crane/


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