Answers from the Whooping Crane
Expert
Spring 2011
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Can male cranes fly faster than female cranes?
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What is the period of imprinting for Whooping cranes?
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What triggers Whooping crane migration?
Teachers: You can use today's Answers from the Expert, along with those from previous years, in these activities suggested in "Learning from Experts". |
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Laura
Erickson |
From: Radisson, Saskatchewan
Q: I live at Radisson, Sakatchewan. When will the Whooping crane be returning this way & where should I look to see them. What is their fly zone?
A: Tom Stehn reported one bird bearing a radio transmitter had already crossed the border (just barely) by April 15. The snow storms in the Midwest are delaying progress, but I’d be watching for them.
From: Garrison-Jones Elementary School, Florida
Q: Who are the Whooping cranes ancestors?
A: Typical Cranes first appeared in the fossil record from the Miocene, 5–24 million years ago. The Tree of Life project is working out relationships based on genetic studies, and we’re going to learn interesting things as the project progresses. You can learn about it at their website.
Q: How long is the beak of a Whooping crane, and how much does the crane weigh when fully grown?
A: The average length of the culmen, or upper ridge of the bill, is 138.5 mm in males and 136.7 in females. This is about 5 1⁄2 inches. The weight of adult cranes in fall is about 15 1⁄2 pounds to almost 17 1⁄2 pounds. Their maximum weight is usually a little heavier than that, in mid-winter, after they’ve recovered from fall migration while blue crabs are still relatively abundant.
From: Epiphany Catholic School, MN
Q: When cranes are migrating, do their eating habits change?
A: During winter, Whooping Cranes feed mostly in estuaries, mostly on blue crabs and clams, and move to upland areas that were flooded or burned, exposing acorns, snails, mice, voles, crayfish, grasshoppers, and snakes. When they leave Texas, they must switch to a freshwater diet of frogs, fish, plant tubers, crayfish, and aquatic insects; and also on insects and waste grains in harvested fields. Once they reach their breeding grounds, they’ll be eating mollusks, crustaceans, aquatic insects, minnows, frogs, and snakes.
Q: Can the male cranes fly faster than the female?
A: That’s doubtful. Most of the time a pair flies together and matches their speeds. Males are larger, but also heavier, so their maximum flight speed is probably similar to that of females.
Q: What is the best thing about your job?
A: I wish I worked directly with Whooping Cranes! But I love my own job of writing about and photographing birds. I get to meet and talk with people who work on cranes during migration, on their wintering grounds, and on their breeding grounds!
From: Maine
Q: What triggers Whooping crane migration?
A: Increasing daylength during late winter and early spring makes birds restless, and their hormones start to surge. The first birds to leave Aransas are usually experienced pairs. They may have been dancing for several weeks, which “revs them up” for breeding, so they are in more of a hurry to return to their nesting areas. But as antsy as they may be to migrate, they usually wait for favorable weather weather conditions to make their long flights.
From: United Kingdom (UK)
Q:
Do you know what the period for imprinting in whooping cranes is?
I assume it is within the first few hours or days of the chick's eyes
opening. Is this so? After that period, would it impossible for
're-imprinting' (onto say a human) to take place? I.e. is the chick
then 'protected' against mal-imprinting onto any humans it might see?
How different is social imprinting from sexual imprinting? Do the
birds in effect 'imprint' on their natural habitat(s) and on their
natural foods as well? When and how does this occur?
A: We don’t know all the critical information about imprinting
in
Whooping Cranes because the kinds of studies that furnish precise data
down to the minute, hour, or day are impossible to perform on a
critically endangered species. People can keep ducklings in captivity
and expose different groups to a human or other species at different
points to compare, and track them to learn the long-term outcomes.
We
can’t do that with young cranes when we need every one of them
to lead
a more normal life.
We do know that cranes imprint on their parents or foster parents,
and
then are apparently virtually always drawn to mates that look like
their parents. From 1975 through 1988, 289 Whooping Crane eggs were
transferred to the nests of Sandhill Cranes in Idaho—210 hatched
and
85 chicks fledged. Sadly, the Whooping Crane young imprinted on
Sandhill Cranes and even though they spent time in flocks with one
another, not one of them chose a Whooping Crane for a mate, so that
population has died out.
There was also the famous case of Tex, who hatched in the San Antonio
Zoo. She had health problems as a chick and so needed to be raised
by
humans. Although researchers spent years trying to get her to mate
with a male Whooping Crane, she never would. Finally, scientist George
Archibald of the International Crane Foundation figured out what to
do. Every spring he “danced” with Tex, who danced with him,
her chosen
mate. He artificially inseminated her with sperm from male Whooping
Cranes, and she finally produced a healthy chick. People at the
International Crane Foundation were so delighted that they named the
little male Gee Whiz. (The name was also in honor of Dr. George Gee,
who did a lot of important research on captive breeding of Whooping
Cranes.)
Birds can’t imprint on food, or they’d be lost when they
reached their
wintering grounds! But they do stay with their parents throughout
their first summer, autumn, and winter, and their parents teach them
how to find different kinds of food throughout the areas where they
spend each season. And they do seem to do a kind of “imprinting” on
the star patterns and/or angle of the sun in the sky where they were
hatched and reared, because whether they follow their parents back
or
go entirely on their own (as the Ultracranes do), they return to
pretty much the exact area where they started out
From Kentucky
Q: : I know this is nothing to do with Whooping cranes but... What can be done or make the most impact by "we the people" to stop the hunting of Sand Hill Cranes in Kentucky? Or do you agree with this new hunting practice as a legitimate way to keep the population in check.
A: Here
is my opinion: The population of Sandhill Cranes is strong and growing
stronger, but
it doesn’t need to be kept “in check” by
hunting any more than the population of robins does. In many states
Sandhill Cranes have staged a wonderful comeback during recent decades
thanks to contributions people have made to organizations like the
International Crane Foundation and to state non-game wildlife programs.
It’s ironic to ask people to contribute money to support nongame
wildlife and then, when those nongame species recover to healthy
population numbers, suddenly name them a game species. Ironically,
in autumn, 2010, Minnesota opened a hunting season on Sandhill Cranes
in the Northwest Region of the state. This is exactly the part of
the state where Sandhill Cranes are the “poster child” for
the Nongame
Wildlife Program.
The overall population of Sandhill Cranes is probably strong enough now, thanks
to so many people supporting programs to bring them back since the 1970s, to
stay strong with a well-managed hunt. Whether or not this is justifiable is
another question.
Laura
Erickson
For the love, understanding and protection of birds.
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