09 April 2005
National Geographic Magazine's 'Crane Cam'
The live camera is set up in the Rowe Sanctuary in Nebraska on the Platte River to monitor migrating sandhill cranes (Grus canadensis). The camera is operational until sometime in mid-April when the migration will be more or less finished. Best viewing may be found in the hours around sunset and sunrise each day.
I've become interested in these large birds since moving here to the midwest. We have quite a few around my home and quite a few pairs now stick around to nest in the area each summer. Their calls sound like no other earthly creature - sort of a repeated, metallic "garooo-a-a" and they fly relatively low around here so you can easily wake up to a 'crane alarm' on most mornings.
In the morning, cranes shuffle up and down the river waiting for the sun to pop up over the horizon. As the sun rises, cranes head out to feed and loaf in the surrounding fields. During the day, cranes "dance" to relieve the stress of migration and strengthen pair bonds. Cranes are very "social" birds and in the evening, congregate in wet meadows before heading back to the river for the night.
Cranes are omnivorous, eating both plant and animal materials. With the abundance of cropland in the Platte River valley, corn makes up nearly 90 percent of their diet, providing carbohydrates for fat production. Wet meadows along the river provide invertebrates that make up the remainder of their diet. Worms and snails provide protein, with the snail shell being a source of calcium that is essential for egg development.
There are six subspecies of sandhill cranes, of which three are migratory and three non-migratory. Two of the non-migratory subspecies are endangered: the Mississippi and Cuban sandhill crane. All of the migratory subspecies pass through Nebraska and their populations are thriving (~600,000). The most numerous is the lesser sandhill crane, which is the smallest subspecies. The Canadian sandhill crane comprises about 15 percent of the birds staging along the Platte, and the greater sandhill crane about 5 percent.
The wings of a crane are approximately six feet long. Cranes are lazy fliers, relying on thermals to carry them along. Thermals are rising columns of warm air, and when southerly winds start to blow, you will see cranes testing them for flight conditions. Sometimes during flight, the upward wingbeat is very quick, giving cranes a mechanical look. Cranes ride thermals so efficiently that they have been seen flying over Mt. Everest (~28,000 feet).
An adult sandhill crane is between three and four feet tall and weighs 6 to 12 pounds depending on the subspecies. Adults have bright red skin patches on their crowns and are usually gray with brown stains. Juveniles have brown skin patches and can be dark grey to brown in color. Crane's can also stain their feathers by preening after they have been probing the ground for food.
Their bills and feet are important tools. A crane's bill is very sharp and sturdy, useful when probing frozen soil. The edges are serrated to grasp slippery food like worms and snakes. Not only is it used for preening, it is also used as a weapon.
The feet and legs work in conjunction with the beak. The foot has three long toes with claws on the end. These claws are very sharp and can be used for scratching in dirt to find food and for protection. When a crane is threatened, it will use its wings to maintain its balance and then jump up and strike at the attacker with its feet.
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