Journey North Whooping Crane Spring 2006

Responses to Challenge Question #11

Why do you think ALL the Western whooping cranes, including subadults, make the risky migration north to Canada every summer?

Biologist Tom Stehn wondered why non-breeding cranes don't just stay Aransas for 2-3 years until they get mates and are ready to breed. Students who responded did some great thinking about a tough question! Tom adds his thoughts, showing us all that scientists still wonder about many things. For good reasons, some "answers" may always remain uncertain.

What You Said
Seventh graders from Iselin Middle School point out that the trip is a natural part of the whooping crane's life cycle. Others mention the importance of migration for finding foods for themselves and their young. Several of you think that cranes head north to escape the heat. (Read their full responses.)

Marcus (home schooler, Mt. Airy, MD) thinks that young whooping cranes "want to get to know the migration route" when they are not "in a hurry to get to nesting grounds and raise youngsters." He adds this: "Maybe they need to observe the process of bonding with a mate, making a nest, incubating the eggs, and raising young safely in order to learn some things that may not be known already by instinct." (Read his full response.)

Meet Tom Stehn

What Tom Stehn Thinks:
I don’t really have an answer that I feel confident with. My answer would have two parts, but both may only be partially correct.

It may not be very safe for whooping cranes to summer at Aransas when they are molting and going through a flightless period. There are fewer predators on the nesting grounds in Canada compared to Aransas. Also, what would a whooping crane do at Aransas if a summer hurricane hit the Texas coast? (No hurricanes happen in Canada.) Perhaps facing the dangers of migration twice a year might be the lesser of two evils compared to staying at Aransas.
I think the main reason that whooping cranes migrate every year is that “Mother Nature” has programmed the birds to migrate to take advantage of the tremendously productive northern breeding grounds and yet escape the harsh winter conditions. Most biologists believe that programming occurs through the process of evolution. Birds have to receive very strong programming instructions to give them the urge to migrate such long distances twice a year. Maybe it would be just too difficult a programming job to instruct whooping cranes to stay at Aransas for several years and then start annual migrations.