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Manatee Migration Update: March 1, 2000

Today's Report Includes:

New Manatees in the 'Hood: Comet and Xoshi Released!


"Dear Students,

"Comet and Xoshi were successfully tagged and released at Blue Spring State Park, and Brian and Calista are scheduled for release there today!

"Comet's release on 16 February went beautifully! Comet was active, and was interacting with other manatees, including Peaches, who, you may remember, is the calf of Georgia, a previous captive-release. Within a short time, Comet was exploring the spring run, which is just what we hoped for! We want him to become familiar with this habitat. We are encouraged that he has been socializing with other manatees--that's a very good sign.

"He spent Sat. 2/19 and Sun. 2/20 at Lake Beresford, just north of Blue Spring. By Mon. 2/21 a.m. he'd come back to Blue Spring. It's great that he goes out exploring, then finds his way back! That same day he was swimming up and down the run with "Mossback" another young male, about his same size/age.

"Lately, he's become a little wiley. We've had lots of tips on his tag, looks like he's been moving around quite a bit. Late on 2/24 and early 2/25 he plotted in the south side of Lake Monroe. Susan went there on 2/25 trying to get a visual on him. As of 2/27, Comet was still in Lake Monroe--Jim saw him on Sunday, feeding on freshwater vegetation (Vallisneria sp.) with another manatee!

Challenge Question #6:
"Think about other areas where Manatees are found in Florida, and compare those locations to Blue Spring. What reasons can you think of for releasing the manatees at Blue Spring, instead of some other location?"

(To respond to this question, please follow the instructions below.)

Talking Underwater

"Xoshi's release on 2/22 also went very well! There were 4 manatees in the run when she was released, and two approached her immediately. Jim Reid was underwater to film her as she entered the run, and reports there was lots of vocalizing. If you are underwater, it is easy to hear manatees vocalize, provided there isn't a lot of ambient noise (e.g. boat motors) drowning them out. Manatees squeak and chirp and most of their vocalizations are quite delicate and high-pitched--unexpected the first time one hears them, coming from such a large animal!

"Xoshi swam into the river, just opposite the mouth of the run. The weather has warmed and the river temperatures (69 degrees F on 2/22 a.m.) are nearly the same as Blue Spring Run (72 degrees F). The morning after her release, 2/23, she was plotting a bit north of the run, in the river, but it is not a high quality location. By 2/25, she was still out exploring the river, near Blue Spring.

Challenge Question #7:
"Why do you think manatee vocalizations are delicate and high-pitched?"

(To respond to this question, please follow the instructions below.)

"Bob, Susan, and Dean will be at Blue Spring today for the release of Calista and Brian, and one or two of them will stay the night to track for all our manatees on Thursday. I'll let you know if any one gets a visual on these manatees and, if so, what they are up to.

"In the meantime, I've sent the latest data for Ivan, Comet and Xoshi, which you can look at below. Be sure to plot these locations on your map to track their latest movements."

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

Cathy Beck
Sirenia Project
Gainesville, FL

Driven by Degrees: Discussion of CQ #3
In Challenge Question #3, we asked you "Where is Ivan and what is he doing?"

Thanks to Mrs. Jones' Sixth Grade students in Ohio, who zeroed in on Ivan's location: "Ivan is now near or in the Homosassa River. He is probably eating plants, because that is what they do during the day." John, Grant, Jefferey, and Dan at Canton Country Day School, Canton, OH (

And thanks to New Jersey Seventh Grader, Jana, who said that "I think that Ivan is by the coast of Florida." Iselin Middle School in Iselin, NJ (

Biologist Cathy Beck revealed the key details to answer this question about WHERE Ivan was and WHY he was there:

"Manatees are susceptible to cold-related disease, and in the winter they gather near warm water sources such as natural springs or warm water effluents of power plants", said Cathy. Cold temperatures can be a serious threat to the health of manatees.

Ivan's movements kept him in warm water areas. "During January and early February, it was still cold by our standards and Ivan was spending most of his time lounging in the warm waters of the upper Homosassa River, with dozens of other manatees", Cathy explained. "Later, he made several short and quick moves to the mouth of the Hall's River, but since it was still quite cool here, he spent most of his time in the upper Homosassa. As of 25 February, he was still exploring up and down the Homosassa; I suppose it's too cool yet to leave."

Challenge Question #8:
"Why do you think a large marine mammal like a Manatee cannot tolerate cold water when another large marine mammal like a Whale can?"

(To respond to this question, please follow the instructions below.)

Human Home Range
To put the manatees' travels in perspective, compare them to your own travels. In the past 3 weeks, what is the greatest distance between two places you have visited? Calculate the furthest distance between points within your winter range, then answer this question:

Challenge Question #9:
"How does a manatee's winter range compare to your own? What are your reasons for moving? Why do you think a manatee moves around within its home range?"

(To respond to this question, please follow the instructions below.)

Ranger Wayne's Roll Call

Ranger Wayne Hartley

Here are the latest data from Ranger Wayne Hartley at Blue Spring. Before you analyze the recent data, consider his response to Challenge Question #5 below.

Do the same conditions continue to affect the number of manatees in the run? Also, with warming spring temperatures on the way, when do you predict the winter manatee season at Blue Spring will end?"


Air Temp High(C)


River Temp (C)

Run Temp. (C)

# of Manatees

02/01 6 14 13.5 nt 88
02/07 0 23 13.1 22.5 87
02/08 6 24 14 nt 56
02/10 4.5 23 14.5 nt 80
02/13 10.5 28 17 nt 39
02/16 8.5 28 17.5 nt 12
02/22 5 31 20.5 22.5 4
02/23 11 17 20.9 nt 5
02/24 12 27 20.6 nt 7

*(All temperatures are in degrees Celcius; "nt" = temperature not taken )

Cold Weather Equals Fewer Boaters: Discussion of CQ #4

Last time we asked "What reason can you think of that might have helped decrease the number of boat strikes to manatees this winter?"

Ranger Wayne explained that the answer may lie in the fact that some humans don't like cold weather either:

"We've had a good bit of cold or at least cool weather to keep down the boat traffic."

Temperature Trends: Discussion of CQ #5
In CQ #5, hardworking Ohio Sixth Grade students explained what they discovered in Ranger Wayne's data:

"The pattern that we saw was that the lower the temperature the more manatees would come into the run. The day that it was coldest was December 29. On that day, the air temperature low was 5 degrees Celcius and the high was 21 degrees Celcius. On that day there were the most manatees at 103. This was the highest number of manatees in the table. This was the coldest day and when the temperature was dropping, more manatees were there." Mitchell, Corey and David, Mrs. Jones' 6th grade students Canton Country Day School in Canton, OH (

Ranger Wayne explains this in a little more detail:

"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. This chart of average daily river temperature and manatee count helps demonstrate the connection:


Avg.River Temp.

Avg. Manatee Count










"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."

Thanks to all of the students who submitted their "cool" answers--nice job!

Last Call for Your Best Questions!
Meet Manatee Expert Nancy Sadusky of Save the Manatee Club. She's ready to answer your best questions. But hurry, the deadline is this Friday, March 3.

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 OR #9)
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 15, 2000

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