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Holy Cow! What a Calf

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Manatee "Cow" with Calf
Credit: FWC

Manatee young are called calves. And it's a big event when a manatee calf is born, because manatee reproduction is a slow process. The gestation period for a manatee is about eleven to thirteen months.

Manatee births don't happen very often. Male manatees are not sexually mature until they are about nine years old, and female manatees do not start to reproduce until they are four or five years old. Once they are mature, female manatees only have calves about once every two to five years.

Manatee Babies are Big Too
When born, Manatee calves are about one meter (between 3-4 feet) long and weigh between 37-31 kilograms (60-70 pounds). At birth, they are capable of swimming to the surface on their own and vocalize at or soon after birth.

Mother manatees nurse their young for a long period, and a calf may remain dependent on its mother for up to two years. The female manatee assumes total responsibility for raising the calf. The calf nurses from nipples located behind the mother's flippers and begins to eat plants a few weeks after birth. Nursing takes place under water.

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Video Credit: Oceanic Research Group, Inc.
Photo Credit: FWC

Counting the Blue Spring Calves:

Ranger Wayne carefully counts and records the number of calves each year at Blue Spring. These are his calf counts since 1998.

Ranger Wayne's
Calf Count
2004 08 calves
2003
17 calves
2002
07 calves
2001
10 calves
2000
12 calves
1999
10 calves
1998
08 calves

Monitoring the calf numbers is really important for several reasons. First, manatee reproduction is a slow process, and manatee births are not an everyday event, so researchers closely watch the number of calves. Second, manatee births are even more important because manatees are an endangered species, and so every new birth makes a differenceto the long term future of the species. For the manatee, births are are the counterpart of deaths, and this is a delicate balance.


Try This! Journaling Questions:
  • How many pounds were you when you were born? How long were you? How does that compare to the average weight and length of a newborn manatee? What percent of a newborn manatee was your weight or length?

  • What is the maximum number of calves that a female could possibly give birth to if she began having calves at age four and lived to the age of 60?

  • How does that maximum number of calves change if the female reproduces every five years, instead of every two?

  • If an average Manatee lives to sixty years old, what percentage of its life is spent with its mother if it stays for two years?

  • What evidence indicates that manantees are good mothers?

  • To visualize the changing number of calves each year at Blue Spring from year to year, use the Blue Spring calf counts and prepare a graph of calf counts year by year.

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