Migration: A Dangerous Journey Contributed by Tom Stehn of Aransas National Wildlife Refuge Reading and Writing Connections Take a closer look (click on photo) and you'll see that communications towers are even a danger to the ultralight-led Whooping cranes. Operation Migration Perilous Power Lines and Fences 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 isolated area where practically no one lives. The cranes simply do not see the lines. Why should they even be looking since the only natural danger they have are attacks from eagles? 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 including blizzards or foggy days. When we radioed 6 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 %. Cranes can also hit or get caught in fences, especially when they are built across wetlands. 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 stand in throughout the night. That way, they will hear 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 they may not be able to find an ideal place to stop in some locations. Diseases and Gunshots Whooping cranes share wetlands with many kinds of migrating birds, including ducks and geese, shorebirds, and other wading birds such as egrets and herons. As wetlands are drained in this country to make room for more farm land, migrating birds are forced to concentrate in what is left. These concentrations of birds greatly increase the risk of spreading diseases such as botulism, cholera, or avian tuberculosis. Cranes can also get shot mistakenly by duck hunters or vandals. Fortunately, we think shooting occurs only occasionally, but even once is too often. The new Eastern flock's most valuable adult female was shot to death while at a fall migration stop in 2009. Habituation Getting used 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? This Season Teachers Kids Orientation Registration Search Copyright 1997-2010 Journey North. All Rights Reserved. Questions or comments? Contact us.