Whooping Crane Migration Update: April 18, 2000
Today's Report Includes:
Going. . . Going. . .Almost Gone! Tom Stehn's Crane Countdown
Aransas National Wildlife Refuge
April 17, 2000
Dear Journey North,
After 149 whooping cranes started the migration from Aransas the first week in April, only FIVE birds headed north the second week. I did a census count on April 13 and still had 15 birds here. The count was 20 the week before on April 7. Still present are two nesting pairs. These adult pairs need to get going this week if they are going to have time to make it to Canada, nest, and raise young. But not to worry--pairs sometimes leave Aransas as late as April 20th and still can make it to the nesting grounds in time. I'll do a census again April 20 to see if those adult pairs have started the migration.
Whooping Crane Coordinator
Are you keeping track of Tom's numbers on your log sheet?
What's the Hurry?
If the cranes linger, biologists worry that they won't make it to the nesting grounds in time. Cranes can fly about 30 miles an hour, but when pushed by strong tail winds, speeds of up to 60 mph have been recorded. How many days would it take these remaining two nesting pairs to reach their nesting place in Wood Buffalo National Park? First, pull out a map and figure the distance between Aransas National Wildlife Refuge and Wood Buffalo National Park in Canada. Next, assume good weather and strong tail winds. Use your information to answer:
A Good Week to Fly?
Tom Stehn has told us that cranes usually depart when high-pressure systems bring sunshine to Texas and winds from the south or east. Thermals, and strong southeast winds, provide ideal migration conditions. The least favorable conditions for crane migration are low-pressure systems with north winds because low-pressure systems are associated with storms. Watch the weather conditions in Texas this week to see whether conditions are good for the last cranes to go. These daily weather maps will help you analyze the weather:
The Journey North: Spring Sightings
Wally Jobman writes to tell us where sightings have been confirmed this spring as the cranes head from Nebraska towards Canada.
After you look at the sightings data, see how you might answer:
Setting Up Territory in Canada
Canadian biologist Brian Johns of the Canadian Wildlife Service, knows what to expect when cranes arrive on their traditional nesting grounds. Brian says:
"The cranes usually arrive on the breeding grounds with enough fat reserves left after their 4000 km long migration that they can nest soon after arrival. The cranes feed along the way north, and when they arrive on the breeding grounds they will carefully scout out a location for this year's nest.
"The pairs each defend a territory on the breeding grounds from other whooping cranes. Within their territory they will look for a suitable nest site. It will be one that contains nesting material (bulrush, sedge or cattails) and the right depth of water (usually about 15-30 cm of water, most often in the 20-25 cm range).
"The cranes build a new nest each year. Some times they may nest in the same wetland as a previous year and other times they may move to a completely new part of their territory. The territory sizes vary depending on how close their neighbours are. Average territory size is about 5 square km."
How far in a Day? Response to Challenge Question #17
We asked, "How many miles are whooping cranes known to fly in single day?" For extra credit, we asked you to name a place that's the same distance from your home.
This is a tough one to answer, but Tom Stehn says that with strong tail winds, cranes have crossed Texas in a day by flying 410 miles. Here's how Margaret in Mrs. Patterson's fourth grade at Ashley Academy answered our question:
"Whooping cranes have been known to fly about 600 miles in a day. They could fly from my home to Madison, Wisconsin in a day." Way to go, Margaret! (firstname.lastname@example.org)
Whooping Cranes Learn to Be Parents
Answers to Challenge Question 18
Brian Johns helps us understand these important crane behaviors: "Whooping Cranes are long lived and do not reach sexual maturity for several years. There is a breeding female 23 years of age and two breeding males that are 22 years of age. There also may be older unbanded birds in the whooping crane population. The average age of first breeding for both females and males is 4 or 5 years of age. The youngest wild cranes that have been known to nest have been 3 years of age."
How do whooping cranes learn to be parents? Brian says, "Like most things, the first time you try something new you are not very good at it. However the more times you try, the better you usually become. Parenting in cranes is the same. Basic parental behaviour is programmed into their brains so they know what to do; they just need to perfect the process."
Brian named a variety of reasons why first nesting attempts might not be successful. Maybe the cranes chose a poor quality territory (dry, or lack of food). Maybe the eggs were infertile. Irregular incubation could result in eggs not hatching. And if the parent cranes aren't attentive around the eggs or the young, they could easily be lost to a predator.
We asked Brian what the young must learn from their parents. He replied: "Young cranes must learn many things. Some of the most important are:
It's a tall order! But with practice comes skill. Once they arrive in Canada, we wish this season's new crane
parents lots of success in nesting and raising their young!
How to Respond to Today's Challenge Questions:
Please answer ONLY ONE question in EACH e-mail message.
1. Address an e-mail message to: email@example.com
2. In the Subject Line of your message write: Challenge Question #19 (or #20 or #21 or #22).
3. In the body of EACH message, give your answer to ONE of the questions above.
The Next Crane Migration Update Will Be Posted on April 25, 2000.
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