Crane Coordinator, U.S. Fish and Wildlife Service
was quite surprised when I did a census flight of the whooping
cranes on April 7th and found out
a little over half the flock has started the migration.
Among them were the family group I call Al
and Diane and their twins.That's good news!
year the migration may be slightly on
the early side, but
dangers do you think the cranes would face if they migrated
poor nutritional state of the birds due to the winter food shortage
here at Aransas has not held up the
migration. (I did not expect it to.) Migration behavior
timed to the length of the days that it
never seems to vary
by more than about one week from year to year. As
spring advances, the lengthening days serves as a trigger
to initiate the migration. I have no idea how the
measure or "know" that the days are getting
longer. The birds just somehow get the urge to migrate.
has been such a struggle for the whooping cranes
this winter due to the lack of blue crabs. You can
see in the picture how disheveled the plumage looks,
and how the feathers (which are snow white) have
a touch of gray on them. Photo
Hopefully, the cranes will find much more food to
eat when they reach Canada as they forage on minnows, berries
and insects, a diet found in the freshwater marshes of
Canada that is so different from the salt marshes here
on the Texas coast. Whooping cranes are omnivorous, meaning
they eat just about anything (animals and plants). That
behavior will help them survive through these tough times.
National Wildlife Refuge
After the dry winter with food shortages on the wintering grounds
the cranes can look forward to more normal conditions when they
complete their spring migration. Habitat conditions on the breeding
grounds in Wood Buffalo National Park appear to be near normal.
Snow is in the process of melting. Today's high is +7C but the
temperatures are still below freezing at night.
the winter of 1993/94, the cranes went through an experience
on the Texas wintering
grounds similar to this year's.
of adults were higher than normal, and the cranes were not in
peak breeding condition by spring because of food shortages
during the winter. That year migration was erratic, with some
birds leaving Aransas earlier than normal and other birds lingering
longer than they normally would. Breeding adults were still in
migration when they should have been incubating eggs in Canada.
Once migration was complete, several of the pairs did not nest— likely
because they were in poor condition. This resulted in a 35 percent
reduction in the number of nests from the previous year.
this winter's similar conditions,
it is likely that we will see a reduction in the number of nests
surveys will begin in mid May, when the pairs are nesting,
and we should know at that time if there will be any reduction
in nesting attempts
Saskatoon, SK and
Buffalo National Park