Journey North Whooping Crane Spring 2005

Tom Stehn

Photo Heather Ray

March 30, 2005

Dear Journey North,

I can't tell you exactly how many whooping cranes have started the migration from Aransas because our March 30th scheduled whooping crane census flight was cancelled due to the pilot being sick. The next flight is scheduled for April 6th.
I can tell you this: I was out in a boat at Aransas on March 28th and saw lots of whooping cranes. A few may have started the migration from Aransas in the last couple days as weather provided favorable migration conditions. But it is still early. The majority of the flock always starts migration the first two weeks in April. This allows them to reach Canada just after the ice and snow have melted and build their nests in early May.

One Crane Migrating For Sure
So far, I know of only one whooping crane that has migrated. It's the juvenile
that wintered with sandhill cranes 75 miles north of Aransas. It was last seen
in Texas around March 19th. On March 28th and 29th, this crane was found on the Platte River just east of Grand Island, Nebraska. It normally takes about a week
for whooping cranes to make it from Texas to Nebraska. Even though this
juvenile is by itself (it split off from its parents in the fall migration), it is right on course. I expect it to make it back to where it hatched on the nesting grounds in Canada's Wood Buffalo National Park, where it will encounter other whooping cranes. You may remember that I had anticipated that this juvenile would migrate ahead of the rest of the whooping crane flock since it wintered with sandhills and probably was influenced by them.

Why Do Sandhill Cranes Migrate Earlier than Whooping Cranes?
Last week I asked you why sandhills migrate earlier than whooping cranes, since both species are faced by the same ice and snow conditions if they get too far north too soon. The answer has to do with the breeding behavior of cranes. Sandhill cranes leave first from their scattered wintering areas in Texas and southern Oklahoma. They travel to the Platte River in Nebraska where they will spend multiple weeks in large flocks with about half a million sandhill cranes present. This is referred
to as "staging" behavior," where the migration stops at a specific location
for a considerable length of time. In this unbelievably noisy and confusing mass of grey cranes, the sandhills will pick out a mate and form pair bonds that will last at least through the summer nesting season.

In contrast, pair formation in whooping cranes can take place anywhere at
anytime and doesn't require a spring staging area. Whooping cranes may use
the Platte River in the spring as a migration stop, but they will push on north
as soon as the weather is favorable for the next migration day. Pair bonds
in whooping cranes tend to last for a lifetime, whereas sandhills will frequently choose different mates if they are unsuccessful in raising chicks with their first mate. The staging of sandhill cranes on the Platte River in Nebraska allows for finding different mates. The huge numbers of sandhill cranes on the Platte River in the spring is truly one of the natural wonders of the world.

Tom Stehn
Whooping Crane Coordinator
U.S. Fish and Wildlife Service
Aransas National Wildlife Refuge