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Migration: A Dangerous Journey
Contributed by Tom Stehn, Whooping Crane Coordinator, USFWS

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Take a closer look (click on photo). You'll see that communications towers are even a danger to the ultralight-led Whooping cranes.

Photo: Operation Migration

Perilous Power Lines and Fences
Cranes can hit or get caught in fences, especially when fences are built across wetlands. But the number one problem fo migrating cranes is collision with power lines. Danger can be a huge string of transmission lines high in the air or simply a single wire running into a farm house or irrigation system in an area where practically no one lives. The cranes simply do not see the lines. Transmission lines are hard to see when you are looking into the sun, late in the day when the light is dim, or in bad weather such as blizzards or foggy days. When we radio-banded six whooping cranes back in the early 1980's and tracked them all the way to and from Canada, two of the six died hitting power lines. To make power lines more visible, red plastic balls or similar devices are placed on the lines near airports so pilots can see any lines as they come in to land. When power lines are built across wetlands, the U S Fish and Wildlife Service asks the companies to mark the lines. This reduces bird strike mortality by 50 percent.

Hungry Predators
Whooping cranes potentially face increased predation rates when they migrate. Every night they have to find a shallow pond that is clear from vegetation for them to roost (stand in as they sleep) throughout the night. The shallow water helps them hear and flee any bobcat, coyote, or fox that might be sneaking up on them. But the cranes are unfamiliar with the places where they stop. This increases the danger, and in some locations the cranes may not be able to find an ideal place to stop.

Diseases and Gunshots
Whooping cranes share wetlands with many kinds of migrating birds. Ducks and geese, shorebirds, and other wading birds such as egrets and herons are among them. As wetlands are drained in this country to make room for more farm land or housing, migrating birds are forced to concentrate in whatever wetlands are left. These concentrations of birds greatly increase the risk of spreading diseases such as botulism, cholera, or avian tuberculosis. Cranes can also get shot by vandals or duck hunters. Fortunately, we think shooting occurs only occasionally, but even once is too often. The new Eastern flock's most valuable adult female, #217, was shot to death while at a fall migration stop in 2009.

Habituation to Humans
Getting habituated or accumstomed to humans is one of the greatest dangers that Whooping cranes face. Being even a little tame puts them at greater risk from vehicle collisions, predation, and illegal shooting.


Explore: The Toll from Human Activities

 
  • Over nearly a 40-year period, of 13 cranes that died during the migration and were found by people, 5 hit power lines, 4 suffered trauma due to collisions or gunshot injuries, 1 was shot, 1 died in a muskrat trap, 1 may have had a heart muscle disease, and 1 may have had a viral infection. What percentage of those crane deaths were directly related to human activities?
  • Read the press release from a Texas poacher killing a whooping crane in November 2003. What happened later? Do you feel justice was served? Explain.
  • Tom Stehn says, "If humans could minimize these impacts to cranes, the whooping cranes would do just fine. But humans continue to build more power lines, cell towers, and fences, and the whooping crane remains very much endangered." Humans are part of the problem but also part of the solution. What actions do you think people should take to help minimize the dangers to cranes during migration? If cell towers are being built in your community, find out who to contact. Your opinion counts!

    NOTE: For more on this subject:

    • You may wish to read and discuss "Faulty Towers," an article by David Malakoff in Audubon magazine, September-October 2001, pp. 79-83.
    • See Towering Troubles. How are our TV and cell phone habits are contributing to the deaths of millions of migratory birds a year?

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