Gray Whale Migration Update: February 20, 2002
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:
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?
(To respond to this question, please follow
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).
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.
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
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.)
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.
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:
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:
1. Address an e-mail message to: firstname.lastname@example.org
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