FINAL Fall's Journey South Update: November 17, 2000
Today's Report Includes:
No Whales Here!
As you're busy today in your cozy classrooms, gray whales by the thousands are plowing steadily south, away from frigid Arctic waters of their summer feeding range in the Chukchi and Bering Seas. Students at Nelson Lagoon school (55.9N,-161W) in the Bering Sea, who live about as close to the whales as anyone can get, have seen their last whales until spring. Journey North just received their letter:
So Where Are They?
"The southbound migration runs past Kodiak (57.76N,-152.53W) from sometime in November to January. The southbound migration is longer than the northbound--lasting approximately 2 months going south and 4 months heading north. In Kodiak we're not sure whether the gray whales we're now seeing are migrants or the seasonal residents that have been here all summer. The latest sightings by Kate Wynne of the University of Alaska's Marine Advisory Program were made by air as she flew from Chiniak (57.62N,-152.17W) to Ugak Island (57.40N,-152.32W), across to Gull Point (57.45N,-152.73W), then outside all the way to TwoHeaded Island (56.90N,-153.31W). Kate did not see migrating whales, but maybe the whales were traveling farther offshore. Migratory whales seem to travel farther offshore on their southbound journey, and nearshore on their return north in the spring."
It isn't surprising that the whale migration is hard to track. After all, these huge sea mammals travel where they're not easy to see. But for tens of thousands of years, gray whales have made the same roundtrip journey--up to 12,000 miles--every year of their lives. Meanwhile, we humans keep trying to learn more about the mysteries of migration.
Blubbered Up and Ready to Go
Winter is about to grip the Northern Hemisphere. Nelson Lagoon students said it's getting colder. Indeed, the ice pack now forming in the sea is one thing that sends whales south. All summer the whales have been feeding in these rich sub-polar seas. By summer's end, they have put on a layer of blubber six to twelve inches thick. The blubber will be an energy reserve during the winter months of migration and breeding, when the whales eat little or nothing. The blubber of pregnant females also helps nourish the calves before they are born, usually the months of December through April.
Early in October, Arctic days shorten and the surface ice pack begins to thicken and expand southward. That's when pregnant female grays, already well into their 12-month gestation, slip south through Alaska's Unimak Pass and begin their extraordinary yearly migration over 5,000 miles to Mexico's Baja California coast. Traveling alone or in groups of two or three, they rest little and seldom pause to feed. They may travel 20 hours and 100 miles each day. They know they must reach the protected and warm lagoons in Mexico before they give birth.
In the next weeks, the pregnant females will be followed by nonpregnant females and then adult males. Last of all come the juveniles. Every year of their life, these gray whales travel farther than any other migratory mammal on Earth. How do they know were to go? Send us your ideas for:
The waters of the whales' summer feeding grounds are salty. How does salty water affect the rate at which water freezes? Take a few minutes to think about this. Do you think salty water will freeze faster or more slowly than fresh water? Why or why not?
You can find out by following these steps:
1. First, create water as salty as the ocean. To do this, fill a cup with 4 ounces of warm water, drop 5/6 teaspoon of salt into the water, and stir until the salt is dissolved.
2. Measure 4 ounces of tap water into a second cup.
3. Check to make sure the water in both containers is the same temperature to start with. Then pour the salty water into one ice cube tray and the fresh water into another ice cube tray.
4. Put both trays in the freezer. Predict what you think will happen. Then observe to see which one freezes first. (Start early in the day to allow enough time for the water to freeze while you can still keep an eye on it.)
5. Now describe your results. (If one of the trays freezes first, form a hypothesis about what caused the difference.)
Watch the Arctic Icepack
Now that you're thinking about saltwater freezing, watch what happens to the saltwater in the whales' Arctic home. Using this Web site, you can follow the freezing of the ice pack all winter and the thawing of the icepack next spring:
Something strange is happening to gray whales. Biologists are perplexed and worried about a sudden increase in the number of adult whales that have turned up dead over the last two years. At the same time, births of gray whales are declining. And both trends appear to be accelerating.
Will this trend of more deaths and fewer births continue? Please join us next spring as we track the gray whales' Journey North. With the help of researchers, we may learn some answers--and raise more questions!
Birds of a Feather Flock Together: Response to Challenge Question #8
Last time we talked about robins. Our question asked: "List some advantages birds would gain when they flock together rather than defending territories against one another."
You've heard the old saying, "There's safety in numbers." Flocking means having many more eyes to spot predators and new food resources. It mans many more bodies to distract predators. And think of the energy a robin saves by not having to defend a territory. Flocking sounds like a smart strategy!
How to Respond to Today's Challenge Questions:
1. Address an e-mail message to: email@example.com
Join us next spring, when these questions and other whale migration mysteries
will be explored.
This is the FINAL Journey South Update. Watch for "Signs of Spring" beginning February, 2001!
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