Within the United States, West Indian manatees are concentrated in Florida in the winter, but they can be found in summer months as far west as Texas and as far north as Virginia. They may rest submerged at the bottom or just below the surface, coming up to breathe on the average of every three to five minutes. When manatees are using a great deal of energy, they may surface to breathe as often as every 30 seconds but have been known to stay submerged for up to 20 minutes. Contributed by Save the Manatee Club where you can read much more - Above: A mother manatee and calf. (Photo © Kim Walker Stanberry)
When the surrounding waterways get colder, manatees move into the springs, such as Blue Spring on Florida's east coast, to keep warm. (Photo © Walker Stanberry)
If you live "up north" you know that fall has arrived when
the leaves turn color and snow flurries signal the start of winter.
In Florida, the changes are much more subtle. But we know for sure that
winter has officially arrived when manatees appear at warm water sources
around the state.
Manatees need warm water to survive. In spite of their size, they have relatively little body fat, and their metabolic rate is low compared to other marine mammals. Manatees cannot tolerate temperatures below 20 ° C (68 ° F) for long periods of time. Researchers believe that individuals affected by the cold cannot produce enough metabolic heat to make up for heat loss in the environment. During winters in Florida that have been unusually cold, an increase in manatee mortality has been documented.
Manatees swimming in the tranquil freshwater springs of Florida. See more of our video picks of Manatees: Manatee Interaction Guide For Kayakers
Because of their susceptibility to the cold, the space or range that manatees require is influenced by seasonal change. Florida manatees are considered to be somewhat migratory animals. Generally speaking, they are found in shallow, slow-moving rivers, bays, estuaries and coastal water ecosystems of the southeastern United States. They can live in fresh, brackish or salt water.
In the summer months, manatees travel freely around Florida's rivers and coastal waters. A few manatees may range as far west as Texas and as far north as Virginia (one manatee was even documented in Cape Cod, Massachusetts!), but these sightings are rare. Sporadic summer sightings in Alabama, Georgia, and South Carolina are relatively common.
In the winter, usually November though March, the manatee population is concentrated primarily in Florida. Water temperatures that fall below 21° C (70° F) cause manatees to move into warm water refuge areas. Scientists don't know what cues manatees follow, but they seem to know when cold weather is coming and seek warm water areas.
Travel corridors, or passageways, are necessary for manatees to move back and forth between summer and winter habitats or between feeding and resting or calving areas. It has been documented that many manatees have preferred habitats they return to each year.
|Manatees gather at the warm water effluent of Florida Power and Light Company's Riviera Beach power plant. (Photo by Cynthia Taylor, Wildlife Trust)|
When the weather cools down, manatees gather near natural springs such as Blue Spring on the east coast of Florida or in the Crystal or Homosassa Rivers on Florida's west coast. These springs are winter refuges for manatees because the water temperature is relatively constant throughout the year averaging about 22 ° C (72° F). When the surrounding waterways get colder, manatees move into the springs to keep warm. Please read "Manatee Interaction Guide For Kayakers" before venturing to these locations.
Manatees also gather at warm water effluents of power plants like the Tampa Electric Company in Apollo Beach or Florida Power & Light Company in Ft. Myers or Riviera Beach. Power plants have probably extended the manatee's winter range. At one time, researchers believe, manatees only ranged south of Sebastian Inlet and Charlotte Harbor in the winter. As coastal development pressures in southeast and southwest Florida have pushed manatees further north, power plant effluents have played a critical role in manatee protection.
Unfortunately, warm water sources for manatees are at risk of disappearing as aging power plants go offline and spring flows are affected by Florida's growing human population and its water needs. Such loss of warm water habitat could result in catastrophic manatee die offs during cold winters. The maintenance of warm water refuges will be an important factor in the manatee's future survival potential. We need to make sure that spring flows are maintained and devise warm water alternatives before power plants go offline.
Lifespan, Mortality, Population:
Manatees are seriously endangered. Please read TopKayaker.net's Manatee Interaction Guide For Kayakers before exploring waters occupied by these graceful gentle creatures.
rate for manatees is low. Female manatees are not sexually mature until
about five years of age. Males are mature at approximately nine years
of age. On
average, one calf is born every two to five years, and twins are rare.
Intervals between births range from two to five years. A two-year interval
may occur when a female, or cow, loses a calf soon after birth. The gestation
period for female manatees is about a year. Male manatees assume no responsibility
for raising the calf. Mothers nurse their young for one to two years,
so a calf may remain dependent on its mother during that time. Newborn
calves are capable of swimming to the surface on their own and vocalize
at or soon after birth.
West Indian manatees have no natural enemies, and it is believed they can live 60 years or more. Many manatee mortalities are human-related. Most human-related manatee mortalities occur from collisions with watercraft. Other causes of human-related manatee mortalities include being crushed and/or drowned in canal locks and flood control structures; ingestion of fish hooks, litter and monofilament line; and entanglement in crab trap lines. Ultimately, however, loss of habitat is the most serious threat facing manatees today. There are approximately 3,000 West Indian manatees left in the United States.
Your Voice Can Help Prevent A Current Threat To Manatees:
Florida recently approved an application by Leeward, LLC to develop a 128-slip marina on the Orange River in Lee County, Florida. The property is just downstream from the Florida Power and Light (FPL) plant's warm water discharge, which has attracted nearly 500 manatees to its warm waters during the coldest winter days. (see photo, right) Leeward is trying to turn a dilapidated and predominantly unusable boating facility into a bustling marina. This basin is not just a travel corridor but a critically important manatee habitat component. In fact, hundreds of manatees on a single day have been counted resting in the passive warm-water basin that would become the marina. The marina would be sited in the state's deadliest river system, within the deadliest county for manatees. Its proposed location downstream from a major winter manatee refuge further illustrates that this development must be stopped! The Marine Mammal Commission recently wrote a letter to the U.S. Fish and Wildlife Service stating that the Service's Biological Opinion of this project does not adequately consider:
What You Can Do:
Add your voice to this effort. Read the full letter and plan here at the Save The Manatee Club website: "Lee County Manatees Need Your Help! Proposed Marina Threatens Nearly 500 Manatees".
>>>Please continue on to: "Manatee Interaction Guide For Kayakers, Including How To Choose An Outfitter"
All facts, photos & copy contributed by: Save the Manatee Club with some minor edits by TopKayaker.net - The Florida Manatee Recovery Plan was developed as a result of the Endangered Species Act. The recovery plan is coordinated by the U.S. Fish & Wildlife Service (USFWS) and sets forth a list of tasks geared toward recovering manatees from their current endangered status. Save the Manatee Club is part of the Manatee Recovery Team, which carries out the tasks in the plan under the auspices of the USFWS. In addition, SMC is part of the Manatee Technical Advisory Council, which makes recommendations to government officials on manatee protection issues. To participate, contribute and learn more visit savethemanatee.org - Permissions granted by Nancy Sadusky Director of Online Communications, SMC.
Books: Manatees, Gentle Giants in Peril by Mary Unterbrink
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