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Answers from the Whooping Crane Expert

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Answers from the Whooping Crane Expert
Special thanks to ornithologist Laura Erickson for providing her time and expertise in responding to your questions below.


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From: Lincoln, Nebraska

Q: How many Whooping Cranes migrate from the Aransas/Wood Buffalo preserve to Canada on an annual basis? What percentage of the cranes that migrated from the Aransas/Wood Buffalo Flock typically stop in Nebraska on their way north?

A: This past winter a record number of Whooping Cranes wintered in Aransas National Wildlife Refuge: 194. These are the birds that breed in Wood Buffalo National Park in Canada. Only a very small percentage of them stop in Nebraska on their way north. They cover very long distances on migration, choosing to move on days with perfect migrating conditions--lots of thermals to carry them aloft with minimal effort.

Q: What time of year do they typically stop? How long do they usually stay? Where (I assume somewhere along the Platte River) do they prefer to stop?

A: Ones that drop in on the Platte River stay for several days or up to a few weeks.

Q: How many Whooping Cranes are there in all the known populations?

A: As of Feb. 2004, there were 194 in the Wood Buffalo/Aransas wild flock, at least 83 in the non-migratory Florida flock, and 36 in the Wisconsin/Florida migratory flock, making a total of 313 wild cranes. There are also 119 captive cranes, making a total world population of 432. You can keep track of crane numbers by clicking here.

Q: What are the best estimates of how many Cranes there were before they began to be adversely impacted by anthropogenic activities?

A: Whooping Cranes were never abundant, as far as we can determine. The population in the 1850s was probably somewhere between 1300 and 1500 birds.

Q: What is the number (the restoration goal) of Whooping Cranes in the population that is needed before the USFWS can downlist them from endangered to threatened?

A: The Whooping Crane restoration team has decided that in addition to the Aransas/ Wood Buffalo flock, two additional flocks of 25 breeding pairs each (the Wisconsin/Florida migratory flock and the non-migratory Florida flock) will be needed to improve population health to the point that whooping cranes could be downlisted from endangered to threatened under the Endangered Species Act.

Q: Are there any critical habitat limitations that are adversely impacting population recovery? If so what are the limitations and how many birds could the known habitat sustain if something is not done to improve it?

A: Whooping Cranes require extensive wetlands for breeding, wintering, and migratory stopovers. The blue crab population where they winter is critical to their breeding success the following summer. They suffer when the rivers feeding into their wintering estuary are depleted of water as a result of droughts and from people diverting the water for other uses.



From: Marilyn Beale


Q: What caused the depletion in the numbers of whooping cranes so that we need to help them?

A: During the 1800s, Whooping Cranes were over-hunted. At the same time, wetlands were being drained for agriculture. During the mid- and late-1900s, even as more wetlands were being drained and developed, pollutants were increasing, and more water was being taken from rivers feeding into the estuary waters where the Whooping Cranes spend the winter. This caused their population to crash to a critical level.


From: White Bear Lake, Minnesota

Q: It is amazing that the whooping cranes seem to leave their wintering grounds at almost the same time each year. Why is this? What factors signal the cranes that it is time to leave?

A: Birds become increasingly restless during their migration season as a response to day length, which changes the same from one year to the next. But to actually act on this restlessness and head north, Whooping Cranes take advantage of certain weather conditions--little or no wind, or tail winds along with enough sun to produce thermal air currents, which happen on only a few days. And they're social birds, taking their cues from others in their flock. On average, these happen pretty much at the same time each year.


From: Victoria, Minnesota

Q: Why do you think that the groups continue to split up during migration? (After all, didn't they all fly south together and stay together on the wintering grounds?)

A: Whooping Cranes are not gregarious birds like finches that like to flock in huge groups. They are sociable, so we almost always encounter family units, pairs, and small groups of unpaired young. There is probably something in their genes that makes cranes most comfortable in these small groups.

Lobstick Family at Aransas NWR
Photo Diane Loyd

Q: Do these families usually migrate together? What advantages or disadvantages might there be if they migrate together? Or migrate apart?

A: The family group stays together for all of autumn migration and then much of spring migration, before the parents push on without last year's young. More eyes make it more likely that at least one of them will spot a predator in time for the whole group to escape. The parents are warier and more experienced than last year's young, and the chick will benefit from staying with them as long as possible. And the migration route experience of the parent birds gives an advantage to last year's chick, too; the parents are more likely to know good resting and feeding places, which is especially important for inexperienced young birds when they're following a different route in spring than they did in fall. But as a pair gets closer and closer to its breeding ground, its need for isolation becomes greater than its concern for its young, and the parents move on without them. One disadvantage of being in a group is the greater competition for food. In non-related groups, there is even--to some degree--competition for mates, which could lead to the breakups of established pairs, or a waste of energy in extra displays to show which birds are mated pairs. It will be fascinating to see how the young cranes in the Wisconsin/Florida flock break up and form pairs as they mature in the coming years.

Dr. George Archibald dances with Tex (see story) , who thinks she's his girlfriend.
Photo
International Crane Foundation

Q: Before in one of your updates there was something on how experts tried to raise the whoopers with sandhill cranes, but they imprinted and would only mate with sandhills. There was also something on how one whooper imprinted on a human and that person had to jump up and down and flap his arms every year to get it to lay eggs. If I'm correct on this, does that mean that the whooping cranes don't do any physical contact when breeding like we do? Is it more of a mental thing? I'd like to know more; I don't understand. I know they do the dance with each other, but is that it?

A: Crane pairs dance to prepare for mating, in the way that human couples date and have romantic evenings before they marry. Dancing helps each crane pair to be in perfect physiological synchrony so the females will ovulate and be receptive to mating right when the males are most capable of producing sperm. But to actually mate, the cranes must come into physical contact.


From: Montrose, Minnesota

Q: How could it be that we saw a pair of whooping cranes here in Montrose, Minnesota? Could they possibly be nesting nearby or are they migrating?

A: These birds were seen in April, which is migratory season, and were confirmed as wanderers from the Wisconsin flock. In spring or fall, they could also be birds passing through between Aransas and Wood Buffalo.

Q: Could they be part of the Wisconsin flock and only here for the day? What is this dancing, soaring thing they were doing? It was magnificent.

A: The Wisconsin flock has been doing a bit of wandering, which is normal for subadults. The dancing cranes do is partially a part of their mating behavior, and since you were seeing a pair, it's possible they were a breeding pair. But young birds often dance, and in migration, as hormones are revving up, often birds seem to dance as an aggressive behavior. To see photos and a video of a pair of cranes dancing at the Patuxent Wildlife Center, click here.


How to Use FAQ's About Journey North Species
Since 1995, experts have contributed answers to students' questions about each Journey North species. These questions and answers are archived in our FAQ's (Frequently Asked Questions) section. You can use today's Answers from the Expert above, along with those from previous years, in the activities suggested in the lesson, "FAQ's About Journey North Species"


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