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Gray Whale Migration Update: February 20, 2002
Today's Report Includes:
- Latest Migration News: Challenge Question #4
- Holy Cow! Good News About Calves
- Southbound Babies? Discussion of Challenge Question #2
- Classroom to Classroom: Alaska-to-Mexico Exchange
- Two Letters: Mexican Students Like Their Whales
- Try This! Draw a Life-Size Whale
- A Whale of a Baby! Response to Challenge Question #1
- Reading the Data: Response to Challenge Question #3
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Gray Whale Migration Route |
How do we know there are LOTS of whales in the birthing and mating lagoons of Mexico? The number of southbound whales past the census station at Point Vincente, CA. is slowing. Since our last report, 55 whales have been counted, and the northbound migration hasn't really begun. That must mean most whales are in the lagoons, as expected. The latest data tells the story:
- Link to Latest Migration Data (Feb. 5-18)
ACS census volunteers Mike and Winston point out something to watch for: "To date, we have not yet seen the crossover (or turnaround, when we start seeing more gray whales going north than south). I would expect to see this happen within the next week or so, as the southbound daily count numbers are getting low. Last year the crossover began around February 23rd, but we are dealing with Mother Nature, so anything can happen." That's Mike's prediction; when do YOU think the crossover (turnaround date) will be?
Challenge Question #4:
"What date do you predict will be this season's turnaround date, when whales northbound will exceed whales southbound?"
(To respond to this question, please follow
instructions below.)
Scientists and whale watchers note that the southbound is running a bit late this year. Could it be that the grays
are lingering in the nutrient-rich waters of the north to fatten up before making the long journey south? No one
knows for sure, but the late migration could be hard on mothers with babies born before they can reach the lagoons.
Holy Cow! Good News About Calves
On February 12, Mike and Winston reported this good news: We now have the 4th highest southbound calf count out of 19 years of censusing: 35 calves out of 392 southbound gray whales. This compares to 11 calves out of 439 southbound migrants last season, and 2.5% calves as of end of the last season).
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Rating |
Newborns |
Year |
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Highest |
106 |
1997-98 |
|
2nd |
44 |
1996-97 |
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3rd |
43 |
1993-94 |
|
4th |
35 |
2001-2002 |
|
5th |
34 |
1995-96 |
BUT: Many of this year's calves were born before their mothers reached the warm, safe lagoons of Baja Mexico.
Steph Dutton and Heidi Tiura, who own Sanctuary Cruises in Moss Landing, Calif., have spotted four early calves
so far. Steph described one pair: "The mother was swimming beneath the calf, lifting it up to help it breathe."
Dutton and Tiura said they watched other pairs that seemed to be struggling through Monterey Bay and yet appeared
determined to press on to the warmer, saltier and thus more buoyant waters in Baja California's lagoons.
What does birth
while migrating mean for the calves? Dave Rugh (say "Roo") is a wildlife biologist with the National
Marine Mammal Laboratory in Washington told us: "I wish I had an unequivocal answer to the question about
survivability of gray whales born in the Baja lagoons versus those born while migrating. However, we do not have
data on the percentage born within the lagoons, nor can we trace the fate of those that were born elsewhere. Adult
whales have been observed leaving a lagoon and returning with a calf, so the lagoons are not critical for birthing
as much as they may be advantageous as a nursery. The relatively protected, warm waters reduce heat loss. Many
calves are born well north of the lagoons (shore-based observers in central California count dozens in spite of
the difficulty of seeing a whale calf from shore), so we can assume they have evolved the ability to being born
at sea outside of the protection of the lagoons."
Southbound Babies? Discussion of Challenge Question #2
Last time we asked: "What might be some difficulties for baby whales born during the southbound migration instead of in the warm, shallow lagoons?" Fifth Graders from Ms. Thurber's class at Ferrisburgh (VT) Central School had this good answer:
"Babies born during the migration might have some difficulties because they do not have as much blubber when they are born as the older whales. Blubber is what allows the whales to maintain their body temperatures in colder waters. The water is colder during the southbound migration than it would be in the lagoons. It would take more energy to stay warm in the colder water. The babies would also have to swim more because they are in the middle of the migration. They might not be able to eat enough to keep their strength up."
Scientist Wayne Perryman agrees: "If a calf is born along the migration route it will be required to migrate instead of just hanging around. This, you would think, would cause it to burn more energy. Calves are born skinny, with little or no insulative blubber layer so they will also burn up some energy keeping warm. The water in the lagoons is not only warm, but the salinity is very high. That means that calves can float easily to the surface in the high density water while those born in the lower salinity waters along the California coast may have to swim to the surface, and the higher waves can make them more vulnerable to drowning. Probably the most important disadvantage of being born along the migration route is the killer whales can find you. There are no killer whales in the lagoons so it is a safe place if you are a calf."
Classroom to Classroom: Alaska-to-Mexico Exchange
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Alaska or Mexico? |
Alaska or Mexico? |
One of these landscapes is the northern end of the whale migration trail in Alaska. The other is in the warm
birthing lagoons of Mexico where the whales are right now. Which is which? What makes both locations look similar
in these photos? (If you still wonder, see our February 6 Gray Whale report for clues.)
Would you like to meet school children who live at both places in the photos above? Journey North's Jane Duden
visited Laguna Ojo de Liebre last month to see the whales and to introduce two schools from both ends of the whale
migration trail. The schools exchanged letters and gifts to help them learn about each other and the whales that
share their environment part of each year. Here's the letter Mrs. Concilus (teacher at Nelson Lagoon School) wrote
to introduce her town and students to the students in Mexico:
Now take a photo tour of both schools! Meet the students in the far north at Nelson Lagoon School and in the far south at Amado Nervo School in Guerrero Negro, BCS (Baja California Sur, Mexico). Captions describe the photos.
- Meet Students at Amado Nervo School in Guerrero Negro, BCS
- Introducing Nelson Lagoon School in the Aleutian Islands, AK
How did you do on the Alaska Artifact Quiz in our February 6 report? In our next report, photos let you join the students at Nelson Lagoon looking at the gifts sent to them by Amado Nervo students! We'll also have a photo tour of Guerrero Negro, Lagune Ojo de Liebre and more whale watching. Read on for more from the Mexican students.
Two Letters: Mexican Students Like Their Whales
Jacqueline
from Amado Nervo School near Laguna Ojo de Liebra wrote this in her letter to students in Alaska: "We can
also brag about the Grey Whales visiting us. They come every year looking for our water to breed and reproduce.
You can't imagine what a great sight it is." What does Imelda, another 6th grader from Guerrero Negro, have
to say about gray whales? Read both letters:
- Link to the English translation of Jacqueline's complete letter
- Link to English and Spanish versions of Imelda's letter
Try This! Draw a Life-Size Whale
After reading
their letters (above), you may be even more curious about the whales that spend the winter where Imelda and Jacqueline
live. What if your heart weighed 285 pounds (130 kilograms)? What if your eyeball was the size of a baseball? You
might be a gray whale! Use our verbal clues to draw a life-size gray whale and you'll find out just how BIG these
creatures are! For directions and more,see:
A Whale of a Baby! Response to Challenge Question #1
"About how much will a calf weigh by the time it is two months old and begins the long migration north? Why is a calf's weight gain important?"
We heard from several mathematicians, but everyone forgot to add the calf's weight at birth! Here's how it goes:
Iselin Middle School 7th graders were right when they said the babies put on blubber to protect them as they migrate; the blubber keeps them warm and provides energy for swimming. They also correctly figured the amount of weight the calf gains in two months: "There are 60 days in 2 months. The calf gains approximately 60 pounds in a day. So we multiplied 60 times 60 which equals 3600." BUT A calf weighs about 800 kg or 1760 pounds at birth, so the birthweight plus the gain is a total of about 5360 pounds. Good try!
Reading the Data: Response to Challenge Question #3
We asked: "How many southbound gray whales did ACS count BEFORE January 23? Compare the number of southbound whales for Jan 25-Feb 1, 2002 to the AVERAGE number of southbound whales for the same week over the last ten years."
If you did calculations with the season-to-date and current data from last time, you found that 298 whales were counted before January 23. During the week of Jan 25-Feb 1, the season-to-date total was 372 whales. The 10-year average for the same week is about 452 whales, so the season's numbers are lower--but still higher than the 10-year average for least number of southbound whales for the same week.
TIP: You can keep up with the daily gray whale census counts for yourself (great for graphing!) on the ACS Web site:
How to Respond to Today's Challenge Question:
IMPORTANT: Answer only ONE question in each e-mail message.
1. Address an e-mail message to: jn-challenge-gwhale@learner.org
2. In the Subject Line of your message write: Challenge Question #4
3. In the body of EACH message, give your answer to ONE of the questions above.
The Next Gray Whale Migration Update Will Be Posted on March 6, 2002.
Copyright 2002 Journey North. All Rights Reserved.
Please send all questions, comments, and suggestions to our feedback form
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