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Q. How far is the whooping cranes' migration?

A. The distance between Aransas NWR in Texas and Wood Buffalo National park in Canada's Northwest Territories is about 2,500 miles. Each spring and fall the world's only natural flock of wild migratory whooping cranes makes the annual journey between their wintering grounds in Texas and their nesting grounds in northern Canada. The cranes make the migration in about 2 to 3 weeks.

In 2001-01, a second wild flock of migratory whooping cranes was started in Eastern North America with the help of ultralight airplanes. Cranes lived here over a century ago, and are being reintroduced once again. The new Eastern flock migrates between Wisconsin and Florida, a distance of about 1,225 miles.

Q. When do whoopers leave their wintering grounds in Texas?

A. The first whooping cranes in the Aransas/Wood Buffalo (or Western) flock normally start the migration about mid-March. A few could leave a little before that, but most of the population leaves during the first half of April. Timing is similar for the whooping cranes in the reintroduced Eastern flock, with wintering grounds in Florida.

Q. Why do cranes depart at almost the identical time each spring?

A. The departure schedule may vary by about a week from year to year, but is remarkably consistent. Crane departures are based on hormonal changes the birds are undergoing that are related to the longer days in the spring. The length of day, or photoperiod, doesn't change from year to year, and this is the key trigger to crane migration.

But that trigger simply makes the cranes ready to migrate. The actual take-off happens on days when they get some help from the weather. Ideal migration days have lots of sunlight. The sun beating on the ground makes some areas a bit warmer than other areas: pavement is hotter than lawns, land areas are warmer than lakes and streams. These differences in temperature cause air over the warmer spots to rise, and that movement of air (called a thermal) makes it much easier for cranes to stay aloft. They can fly hundreds of miles in a single day with little work if they get assistance from thermals and other favorable air currents. They would never take off on a day with perfect migration conditions in January or February. Until day length
is right, they won't start out, but once it is, they get to choose the days on which they make their marathon flights.


Q. How do cranes prepare for the journey north?

A. Hormonal changes in the cranes allow them to gain weight and build up the fat reserves necessary for the long migration. They feast on blue crabs.


Q. When do the cranes arrive in their breeding (summer) home in Canada?

A. They usually arrive in late April or early May, just as the ice and snow are melting from the marshes. They have to get up to Wood Buffalo National Park (60 N, -114 W) by early May in order to nest in time. The young chicks will need all summer to grow, learn to fly, and gain endurance for the migration with their parents in fall. Timing is similar for the whoopers in the reintroduced Eastern flock, nesting in Wisconsin.


Q. What do the cranes do first upon arrival back in Canada in the spring?

A. The cranes usually take a few days to check out the territory they held last year before selecting a place to nest.

 

Q. At what age (breeding age) do whooping cranes usually hatch their first young?

A. Whooping cranes usually are 4 or 5 years old when they successfully hatch their first young. Mating and nesting behaviors can appear in cranes three or even two years of age. Inexperienced cranes may not be successful at their first nesting attempts. Parenting takes practice!



Q. What is a whooping crane nest like?

wcrane_onnest_Muir

Crane on Nest. Dalton Muir.


A. Their nests are built on small islands of bulrushes, cattails and grassy wetland plants called sedges. There, the young are relatively safe from predators. The marsh waters also provide food for whoopers. One pair's nest, for example, was in about 25 centimeters of water. The wetland where the pair nested was a mix of open water and sedge. The pair's nest was constructed out of this sedge and was about 1 meter across.


Q. How many eggs do cranes normally lay?

A. Two eggs are normally laid by wild cranes. Usually only one chick survives the summer and the migration to the wintering grounds in Texas. Twins sometimes survive to make it, and you can read Tom Stehn's report about the first twins he saw. The first eggs for the new Eastern flock were laid by two crane pairs in Wisconsin in spring 2005, but the experienced adults accidentally wrecked the eggs shortly after laying them.


Q. How long does it take for whooper eggs to hatch?

A. Both the male and female share incubation duties and they will incubate the eggs for about 30 days before the eggs hatch. See An Inside Story: Visualizing Inside the Egg.


Q. Why is the survival of young Whooping Crane chicks greater during years with high water levels than during years with low water levels in the breeding area?

A. In dry years the entire area is more accessible to land-based predators; family groups have to travel over greater distances to find food in the remaining wetlands and they may run into these predators. Food supplies available to the cranes may also be limited, which adds to the stress on the young while they are growing.


Q. When do young whoopers learn to fly?

A. The young birds fledge at about 9-10 weeks of age, or about 60 days of age. They are very vulnerable to predators at this time.


Q. Do cranes mate for life?
A. Yes. They bond and nest together for life. However, it doesn't always work that way. It is thought that "divorces" sometimes occur among whooping cranes when a pair can't produce young that survive. This is a survival instinct. For more, see Mates for Life.


Q. How fast do cranes fly during migration?

A. They can fly about 30 miles an hour. When pushed by strong tailwinds, speeds of up to 60 mph have been recorded. With strong tail winds, for example, cranes of the main flock may have crossed nearly all of Texas (over 400 miles) in one day. They make the migration from Texas to Canada in 2-3 weeks. Cranes of the new eastern flock can migrate from Florida to Wisconsin in a week.


Q. How far do cranes usually fly each day when they migrate north?

A. They fly anywhere from 200-400 miles a day, often assisted by thermals. As they fly, the whoopers of the western flock are spread out in their north/south corridor over 150 miles in width.


Q. Why is the timing of the cranes' migration so important?

A. The cranes have to balance the need to get to Canada by early May in order to nest in time during the short summer season. But they don't want to encounter severe spring blizzards on the way or have frozen ponds when they reach the Northwest Territories in Canada at the end of April or first week in May.


Q. Why do birds face into high winds, and take off directly into headwinds?

A. Journey North students supplied good answers: They thought that birds fly into the wind because if they go with the wind they'll have no control of where they are going. Also the way feathers are shaped, they would ruffle and may be damaged if the bird turned around. It is more aerodynamic to fly into the wind.


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