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March 30, 2006
Dear Journey
North,
It is still very early in the whooping crane migration. On my March
29 aerial survey, there were only 19 cranes I could not find. With
dark, low clouds making difficult viewing conditions, I’m sure
I overlooked some cranes. Thus, I estimate about 10 cranes may
have started the migration. This
is
a much more
conservative number from last week’s estimate of 20-30. This
new, lower estimate makes sense since, so far, the only confirmed sighting
I know of in the migration corridor are two whooping
cranes
that have reached the Platte River in Nebraska. (One is likely
the whooping crane that wintered with sandhills in extreme south Texas
until
around March
3. Because it was with sandhill cranes, it migrated on their
earlier schedule.)
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Meet The Lobstick Family
On
today’s
flight, I did extra searching for the Lobstick family group of cranes
but they were not located. I think they have headed north because traditionally,
the Lobstick cranes are some of the first birds
to migrate and traditionally reach Wood Buffalo Park before most
other cranes. Their name comes from Lobstick Creek where they nest
just outside
the boundary of the Wood
Buffalo National Park in the Northwest Territories
of Canada. The nesting area is north of Aransas by 2,500 miles, but
still south of the Arctic Circle and south of the tundra, the most
northerly habitat in North America. Instead, the cranes nest in marshes
surrounded by boreal forest.
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Big
Blue Crab
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Tough
Conditions for Cranes at Aransas
Conditions are tough for the whooping cranes at Aransas right now,
with few blue crabs to
eat and high water salinity (the saltiness of water),
forcing cranes to fly inland to get fresh
water to drink. Marsh salinities were measured
between 28 and 38 parts per thousand. This is equivalent
to ocean water. Crab counts conducted March 27-28 with more than 4
person-hours of walking through the marsh found only 7 small crabs.
This number is
very low compared to average crab numbers. It would be equivalent
to you having to walk 4 hours to the store and then being allowed to
buy only 7 small oatmeal cookies that you would have to share with
your parents. The low number of blue crabs in the Aransas marshes is
correlated with the extreme drought over the past
4 months in this part of Texas, making harder conditions for
crabs to survive. The area finally received decent rains March 28,
but
we need a lot more rain to help the crane habitat.
Tom Stehn
Whooping Crane Coordinator
USFWS
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North. All Rights Reserved.
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