first five of the 266 Whooping Cranes at Aransas (say Uh RAN
Zus) left on migration March 25, and several others soon soon
followed. The Lobstick adults with their twin chicks have apparently
started migration sometime in the past week. They are almost
always some of the earlier migrants. So somewhere, a group
of 2+2 is en route. The unbanded family group that winters
close to them has also started the migration. I
plan to fly over the refuge to count the remaining cranes
on April 10.
then, you may recall that last week I asked you to think of reasons
why it would be an advantage
in small groups. Did you think of these advantages and
Advantages of Migrating in Small Groups
Migration that occurs in small groups is a way of spreading out
the risks of all the hazards species encounter when they are
in migration. If there are multiple small groups of cranes
separately, perhaps only one or two groups will encounter difficulties.
If all the cranes migrated together and encountered trouble,
such as a bad spring blizzard, the entire population could
of Migrating in Small Groups
disadvantage of small groups is that the cranes cannot rely
on others . . .
stay on course during the migration, or
watch for predators when they stop for the night during the migration.
crane must be able to survive on its own. Fortunately, cranes
can do this, and some young cranes will actually
migration on their own. They sometimes get help
by joining up with sandhill
cranes in flight or at a migration stopover site.
Cranes Surprise Us
of the time whooping cranes migrate in family groups or bachelor
groups. This general rule helps us determine credible sightings
reported by citizens. If they report a large group of cranes
flying together, we usually believe they are sandhill cranes.
But it seems there's always an exception to every "rule"
as this sighting report proves:
|Click to enlarge this sighting report. |
vast majority of the whooping cranes leave Aransas the first
2 weeks in April, with peak departures normally between April
4-12. Keep your eyes on the skies!
Aransas National Wildlife Refuge