Manatee Home Page

Challenge Questions

Today's News
Today's News

Spring's Journey North
Spring's Journey North

Report Your Sightings
Report Your Sightings

Teacher's Manual
Teacher's Manual

Search Journey North
return to:
JNorth Home Page



Manatee Migration Update: March 4, 1998

Today's Report Contains:

Latest Manatee Satellite Tracking Information

Field Report About Brian

Photo credit:s USFWS
In last week's update, we reported on the retagging of "Brian", a former orphaned manatee who was raised in captivity and then released back to the wild. Since that update, Brian showed several symptoms that made scientists worry about his health and wonder if he could continue living in the wild. Cathy Beck provided these reports on Brian's condition--take a look and see how the scientists and veterinarians decided what to do:

"Bob Bonde was a bit worried about Brian when he retagged him, and now Brian has been at the same site for a couple of weeks. His is very thin and lethargic, and since last Thursday has been fed about 4 cases of lettuce a day. We were worried that he had completely shut down, i.e. could no longer eat, which has happened to others suffering from hypothermia or starvation, or ???. But, he is eating and that is a relief, but he is very emaciated. Why he has not completely adjusted to the wild, or if he has acquired an infection, is the big question. The Sea World vets will probably examine him on Thur. or Friday and decide if he should go back in."

"Brian is still being fed and was observed by a Miami Seaquarium veterinarian yesterday - he agreed he looks thin and is acting lethargic (for a manatee)."

"Brian's capture is set for Monday. I'll let you know how it goes."

" Brian is now in captivity at Miami Seaquarium. He was captured and transported there yesterday (Sun.). He is thin, but eating well now. The vet there thinks he just needs some R & R! Complete physical assessment is pending "

As of February 27, Cathy reported, "Brian is doing well at Miami Seaquarium." Watch the next update for news on Brian's condition. But, in the meantime, using a Florida map take a look at the satellite data at the end of this report for Brian and the previous data, and then see if you can answer this Challenge Question:

Challenge Question # 6:
"What city was Brian located closest to when Cathy Beck reported on February 17, 1998 that Brian has been at the same site for a couple of weeks? "

(Follow the instructions at the end of this report on How to Answer this Challenge Question.)

Field Report About Xena
In our last report, Cathy Beck also said that one of the Manatees was "moving south," This manatee was Xena, and her southward movement was good news because previously she had been staying near the Georgia border, in the northern regions where cold temperatures present greater risks of cold temperature disease like hypothermia. We are sad to report that Xena has unexpectedly died since the last report, apparently of natural causes, but the exact cause is not know yet.

Sirenia Project biologist Jim Reid was in the Jacksonville area and had seen Xena late afternoon on 2/18 and she appeared fine, and later three satellite locations were received on her during the night. When Jim went to put a new tag on Xena on 2/19 , she was found dead. Externally, Jim indicated that she looked good, with no signs of trauma. Test results so far have been inconclusive. Cathy Beck indicated they just don't know yet what happened to Xena, and they wonder if hypothermia or if her recent move south had anything to do with her condition. According to Cathy, a necropsy showed "she had abundant fat and a full GI tract, which are good signs. Even though the carcass was very fresh, her major organs were very badly autolysed, which may be an indication of an extensive internal infection, cause unknown. Blood work that we will submit next week may confirm this, and may yield more information."

We know that Xena had been "moving south", but can you figure out how many miles she has traveled? Review the satellite data at the end of this report and the previous data for Xena and Knicky too, and see if you can answer this Challenge Question:

Challenge Question # 7:
"Between 01/23/98 and 02/19/98, how many miles south did Xena travel?"
"Between 01/02/98 and 02/27/98, how many miles south did Knicky travel?

(Follow the instructions at the end of this report on How to Answer this Challenge Question.)

Answers To Last Week's CQ # 4
"Why do you think a large marine mammal like a Manatee cannot tolerate cold water when another large marine mammal like a Whale can?"

Here are answers from students in Nebraska who saw that the difference is in the amount of blubber, answers from students in New Jersey, and an explanation from Biologist Cathy Beck. After you read them, try the "cool" experiment provided by manatee expert Bob Bonde and whale expert Ann Smrcina!

Photo credit:s USFWS
"The manatee may not be able to live in the freezing waters like a whale because it does not have enough blubber."
Ms. Gayle Kloewer's Class
York Middle School
York, Nebraska

"Manatees are not adapted to the cold water like whales are. Therefore they can not tolerate the cold water."
Sarah Lang
New Jersey

Like Playing In The Snow Without A Jacket
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!"

"Most manatees in the world live in the warm tropics. Although many people do not realize it, Florida winters can be quite cold, even with freezing temperatures! When air temperatures fall, soon after the river water temperatures will fall below the minimum that is comfortable for manatees (20 degrees Centigrade). When this happens, manatees are reluctant to venture away from the warm water sources to feed, because they are not able to endure cold water for long periods of time.

Try This!
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.

Life's A Challenge

Photo credit:s USFWS
Brian illness and Xena'a death are reminders of how difficult it is for a manatee to survive. Think about the many causes of disease and death that manatees face in the wild, and then try to answer the Challenge Question below. Before answering, you may want to review the Florida Department of Environmental Protection's Florida Marine Research Institute

Challenge Question # 8
"What are all the risks that you can think of that cause disease or death to manatees."
"Which ones are "natural causes", and which ones are human-related?"

(Follow the instructions at the end of this report on How to Answer this Challenge Question.)

Answer to Last Week's Challenge Question # 3:

Photo credit:s USFWS
"How does the number of Manatees counted in January 1998 differ from previous counts? What are some of the many reasons you can think of for these differences?

As many of you saw, the number of manatees counted in January 1998 (2,019 manatees) was lower than the count in February 1996 (2,639 manatees), and lower than the counts in January 1996 and 1997 too (2,274 and 2,229 manatees). But it was also higher than the count in February 1997(1,709 manatees).

Thanks to Ms. Kloewer's manatee team, who suggested the recent Manatee count might be due to a lower birth rate of Manatees: "Maybe not as many calves were born this January 1998 as in other months."
Ms. Kloewer's Class
York Middle School
York, Nebraska

However, Dr. Ackerman suggests that there might be a different reason for the lower manatee count, that might have nothing to do with the actual number of manatees that are actually out there. Dr. Ackerman explained that, "we count the animals during cold weather because manatees congregate in known warm water sites, such as natural springs, power plants and deep canals, when temperatures drop. Counts are more accurate when it is cold, clear and windless because manatees move to the surface to warm in the sun, making them more visible. We try to wait for the best combination of these elements before scheduling a survey. We feel that this lower count is at least partly because of the warmer weather conditions this winter. We are hoping to catch another cold spell to do another count in February."

As you can see, the difference in manatees from one count to the next can be the result of many things, and a count can vary by several hundred manatees simply due to weather conditions. Be careful with numbers. They are very exact--but sometimes their meaning may not be so clear.

Stay Tuned
With Manatees and other endangered species, however, scientists do pay close attention to any declining population trends. Therefore, Dr. Ackerman hopes to do another count soon to help refine the estimate of the minimum size of the population. Stay tuned for more "in-flight" information from Dr. Ackerman about the second aerial count.

Ranger Wayne's Roll Call/Answer to Challenge Question # 5

"Recently we got our first zero counts as it warmed!", reported Ranger Wayne from Blue Spring State Park. Compare this to his reports of having "Manatees every day" since November 6th, which are found below in his answer to this Challenge Question No. 5:

"Based on Ranger Wayne's data, can you see a pattern or trend that might explain the changing number of Manatees counted at Blue Spring each day?"

Ranger Wayne provided this explanation of the trend from his data:"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 of mid-February this year, Ranger Wayne said that "this season is the only season I have experienced in this project (since 1977) where we have had Manatees every day since the day of arrival on November 6. We may have had eight and then they left by noon but they were here. Cool temperatures right along, but not cold. We've hardly had frost on the windshields two or three days. Warm spells (80's) were short and a day or two only. Cool at night."

In the Roll Call data below, does the trend continue or are there examples of other factors mentioned by Ranger Wayne?

Roll Call Chart


Air Temp (C)

River Temp (C)

Run Temp. (C)

# of Manatees





















Today's Satellite Migration Data
(Courtesty of the Sirenia Project)

  • Go to Satellite Data Table for Dakota
  • Go to Satellite Data Table for Brian
  • Go to Satellite Data Table for Knicky
  • Go to Satellite Data Table for Bailey
  • Go to Satellite Data Table for Hillary
  • Go to Satellite Data Table for Xena

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:

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.

Reminder: Only 3 Days Left For Manatee Ask The Expert

This Friday, March 6th, is the deadline for questions to be submitted to Manatee Expert Nancy Sadusky. So hurry, put your thinking caps on and we'll post the answers for everyone to see in the upcoming weeks.
  • Click Here for more information about Ask The Expert

The Next Manatee Update will Be Posted on March 18, 1998

Copyright 1998 Journey North. All Rights Reserved.