Manatee Migration Update: March 3, 1999

Today's Report Includes:

Still With Mom? Discussion of Challenge Question #3
Dmitra and Ivan were still together at the time of the last report!

"I don't believe the small differences in their locations reflect an actual separation," said Cathy Beck. But keep watching! Cathy said that "as the weather continues to warm we may see an actual separation, which will likely happen when they settle into a good spring feeding site."

Are Dmitra and Ivan still together now? As you look over the latest satellite data below, what do you notice? What's going on here?

Today's Satellite Migration Data
(Courtesy of U.S. Geological Survey's Sirenia Project)

Challenge Question #6:
"Why do you think there are no data for Ivan in this report? Consider all the possibilites!" (Clue: Dmitra's data signal was interrupted for awhile too, but started again.)

(To respond to this Challenge Question, please follow the instructions at the end of this report.)

How Far Apart Were They?
We also asked you how far apart Dmitra and Ivan were on February 5 based on their longitude locations. On that date, they were 0.021 degrees apart. By using the worksheets from the Latitude, Longitude and Distance Traveled lesson, you would have been able to calculate at their latitude (28.66 N) that the distance between longitude degrees was as follows:

• a change of 1.0 degree longitude = 60.34 miles
• a change of 0.1 degree longitude = 6.034 miles
• a change of .01 degree longitude = .6034 miles

So by multplying 60.34 miles by .021, we learned that they were approximately 1.267 miles apart.

Ranger Wayne's Roll Call & Discussion of Challenge Question #5
 Ranger Wayne Hartley
The number of manatees at the popular Blue Spring "hotspot" changes from day to day. Ranger Wayne explains why:

"Two primary conditions affect the number of manatees present. The chief is water temperature. The colder the water in the St. Johns River, the more animals in the run. The other factor is timing. Their movements in response to temperature are not immediate. For example, if the manatees have been away during a long, warm period they may take several days to get back when the air turns cold. Therefore, counts on a cold day might be lower than expected. Similarly, the count on warm days after a very cold day may have more manatees. Also, they seem to sense the barometric change ahead of a large weather front, and come in ahead of it at times, no matter the water temperatures. Finally, we also see changes as the winter progresses. For example, during the first cold days in November the manatees respond more to cold than they do at this time of year."

As you look at the latest data from Ranger Wayne, can you see these two conditions affecting the number of manatees in the run?

 Date Air Temp High(C) Air Temp Low(C) River Temp (C) Run Temp. (C) # of Manatees 02/5/99 31 12 21.3 22.5 5 02/10/99 32 16 21.3 nt 3 02/15/99 32 4 nt nt 68 02/16/99 23 7 18.5 22.5 23 02/17/99 27 10 18.5 nt 11

Can You Solve this Manatee Mystery?
Over the past four weeks you've learned quite a bit about manatees; where they live, when and why they move, how far they usually travel. Just when you think you know it all, along comes "MO", another Sirenia Project manatee who took a
 Mo Photo: U. S. Geological Survey, BRD, Sirenia Project
very interesting journey last spring! (Click on his photo to enlarge)

Challenge Question #7:
"Summarize what you've learned about "normal" manatee movements. Plot Mo's data and tell us what is so unusual about this manatee? Then venture a guess as to WHY Mo traveled where he did."

By Land, Air and Sea!
 Dr. Bruce Ackerman
A team of over 30 observers in small planes and helicopters recently counted Manatees on both Florida coasts, along with ground crews at power plants and other warm water sites. Dr. Bruce Ackerman, a marine mammal biologist and coordinator of the survey, reported that the researchers conducted two separate aerial surveys. On Jan. 6 they counted 1,873 Manatees, and on Feb. 23 they counted 2,034.

Challenge Question #8:
"Take a look at the chart below of earlier census counts. How do this year's manatee counts differ from previous years? What reasons can you can think of for these different counts?"

Aerial Manatee Survey Results 1991 To 1999
(Courtesy of Florida Department of Environmental Protection)

 Date of Survey Total Count Jan. 23-24, 1991 1,268 Feb. 17-18, 1991 1,465 Jan. 17-18, 1992 1,856 Jan. 21-22, 1995 1,443 Feb. 6-7, 1995 1,822 Jan. 9-10, 1996 2,274 Feb. 18-19, 1996 2,639 Jan. 19-20, 1997 2,229 Feb. 13, 1997 1,709 Jan. 29-30, 1998 2,022 Jan. 6, 1999 1,873 Feb. 23, 1999 2,034

(To respond to this Challenge Question, please follow the instructions at the end of this report.)

Like Playing In The Snow Without A Jacket
In Challenge Question #4 we asked why a Manatee cannot tolerate cold water as well as a whale? A Minnesota third grader (who knows about cold temperatures and probably wears a jacket when playing in the snow too) said "Because whales have more blubber." Anne from Terry Erickson's class, Creek Valley Elementary, Edina, MN, terickso@edina.k12.mn.us

According to Cathy Beck, "whales have a thick layer of blubber under their skin that insulates them from the cold water. Although manatees have a layer of fat under their skin, it is never as thick as a whale's blubber. Also, like you and me, their fat can vary in thickness depending on how much the animal has been eating. If there have been several cold spells and the manatees have not eaten often, the fat layer becomes thinner; then the manatee is less able to tolerate the cold water. It would be like you going out to play in the snow without a jacket!"

Try This--It's Really "Cool"!
Manatee expert Bob Bonde and whale expert Ann Smrcina offer this experiment to help you test "first hand" why cold feels different to a manatee than it does to a whale. This may be a bit messy, but the experience is worth it!

Materials Needed:
• Bucket
• Ice & water
• Rubber gloves
• Crisco (vegetable shortening)
• 2 Thermometers

1. Fill a large bucket with ice water (3/4 full).
2. Fill a plastic bag with Crisco.
3. Put a rubber glove on one hand. Now put that hand into the Crisco, so the glove is fully covered with Crisco.
4. Submerge both hands--one bare, and the other with the glove and Crisco-- into the bucket of ice water.

How long can you keep your unprotected hand in the water?
How long does it take before you can feel the cold through the fat-insulated hand? How long can you keep this hand in the water?

5. Thermometer Test

• Submerge one thermometer into ice water and record the temperature of the water. How long does it take for the thermometer to drop to the temperature of the ice water?

• Next, put a thermometer inside the Crisco-covered glove that you used in the first experiment. Before you submerge the thermometer, make a prediction of how long you think it will take before this thermometer registers the same temperature as the ice water. After you submerge the thermometer, record the temperature each minute.

Reminder: Only 3 Days Left For Questions For Manatee "Ask The Expert"

Hurry up, it's YOUR turn to ask the questions! This Friday, March 6th, is the deadline for submitting questions for Manatee Expert Nancy Sadusky.

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: jn-challenge-manatee@learner.org
2. IMPORTANT: In the Subject Line of your message write: Challenge Question #6 (OR 7, OR 8 )
3. In the body of the EACH message, give your answer to ONE of the questions above.

The Next Manatee Migration Update will Be Posted on March 17, 1999.