It is hard to say how many whooping cranes have started the migration.
On our March 22 census flight, I only found 163 whooping cranes at
Aransas out of the estimated 215 in the flock. However, skies were
dark all day with high clouds covering the sun. Under those difficult
viewing conditions, I never can find all the cranes.
But It's Still Early
I estimate between 20 and 30 whooping cranes may have started the
migration, no more than 14% of the flock. It is still early for
the bulk of the
whooping cranes to head north. I do have some evidence that the migration
- One whooping
crane was present March 11–16
on the Platte River in Nebraska. We believe this was the whooping
crane that wintered with sandhills in extreme south Texas until
3. Because it was with them, it migrated more on the earlier
schedule of the sandhill cranes.
- A birdwatcher
reported seeing 3 whooping cranes northwest
Fort Worth, Texas on March 19. This is right on the expected
migration path of the cranes, and his observation sounded credible.
with the low number of cranes found on the census flight and knowledge
that whooping cranes can leave in late March, it
seems likely that
some are currently flying north.
Whoopers Migrate Together in Flocks?
Why don’t the whooping cranes all migrate together in large flocks?
Wouldn’t that help them watch for predators and find the
route to Canada? Perhaps, but there are advantages to the cranes
in small groups and leaving at different times. Birds that leave
too early may find less food in the colder conditions of early
encounter bad snow storms such as the blizzard that dropped 2
feet of snow on Nebraska on March 20. Cranes that leave too late
to Canada late and miss the best time for nesting, perhaps when
there is less food available for their newly hatched chicks.
is kind of like the expression “you learn from your mistakes."
The cranes that migrate at the right time get rewarded with higher
survival and better reproduction. Thus, the population—through
the process of natural selection— “learns” when
to migrate. You might say they “know” when to migrate,
but it is really the process of natural selection that determines
the best time
to migrate is.
Fresh Water and Blue Crabs
are tough for the whooping cranes at Aransas right now, with few blue
crabs to eat and high water salinity, forcing them to
fly inland to get fresh
water to drink. On the flight, we found
24 of the whooping cranes inland at freshwater ponds and dugouts.
Two days ago, I walked to numerous fresh water ponds looking for
crane tracks and droppings. From the material I picked up, I
shells about the size of the fingernail on my smallest finger. Think
how many of these tiny shelled critters the whooping cranes would
have to eat to get enough calories. Think about all the grinding
up of the
shells their stomachs would have to do to digest all that material
to get the small bits of meat! As I said, conditions are tough for
the cranes right now.
Whooping Crane Coordinator
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