Manatee Season Begins!

Endangered manatees winter at the warm waters of Tampa Electric's Big Bend power plant. (Aerial photo by Jamie Woodlee)

In late November, the air temperature turned chilly in Florida and thermometers dipped into the 50s. That meant only one thing to manatee watchers: the return of our favorite aquatic mammals to warm water sources throughout the state.

Water temperatures below 21° C (70 ° F) usually cause manatees to move into warm water refuge areas. In spite of their size, manatees have relatively little body fat, and their metabolic rate is low compared to other marine mammals. These factors may account, in part, for their susceptibility to cold temperatures. Generally, temperatures below 20 ° C (68 ° F) are considered too cold and are potentially lethal to manatees.

In the winter, usually November through March, the manatee population is concentrated primarily in Florida, and manatees gather near natural springs or warm water effluents of power plants. There are several warm water refuge areas for manatees in the state. We checked in with Kari Higgs, a biologist with the Florida Fish and Wildlife Conservation Commission (FWC), and Ranger Wayne Hartley at Blue Spring State Park. Here’s what they had to report:

A few snouts and a tail or two show researchers that manatees are present in the TECO warm water discharge canal. (Photo by Jennifer Johnson, FWC)
A closer shot of the manatees gathered at the Big Bend Power Plant. (Photo by Jennifer Johnson, FWC)

Tampa Electric Company's Manatee Viewing Center
When the temperature in Tampa Bay drops below 20 ° C ( 68 ° F), you’ll find manatees at Tampa Electric Company’s (TECO) warm water discharge canal near Apollo Beach, Florida. And where you find manatees, you’ll find researchers. FWC researchers use photography as a means of documenting individual manatees when they gather at TECO’s Big Bend Power Plant.

Kari Higgs, who heads up the Manatee Photo-Identification program at the FWC’s Fish and Wildlife Research Institute in St. Petersburg, Florida, reported that small numbers of manatees had been present in the discharge canal since late October. When we first contacted her, the water temperatures had not dropped significantly yet, and she observed that the majority of manatees at the plant were moms with calves and juveniles.

“When water temperatures drop, often in association with a cold front, manatees seek out warm water,” said Higgs. “When or what exactly triggers a manatee to head for a warm water source most likely depends on the water temperature in its current location, the size of the animal, its distance from a warm water source, whether or not it currently has a calf, the size of the calf, and other variables.”

On November 17th and 18th, right before the cool weather moved in, FWC staff noted that a minimum of 30 adults and subadults and seven calves were present in the discharge canal, which registered 33.8 ° C or 92.8 ° F, a temperature considerably warmer than the surrounding bay waters.

A mother and calf surface to breathe. (Photo by Jennifer Johnson, FWC)

“The predominant activity of manatees in the discharge canal is resting, either at the surface or at the bottom of the water column, while they stay warm,” said Higgs. “However at times you will see manatees moving around the canal, nursing, and/or doing what we call cavorting, which is interacting, splashing, chasing, etc. in groups. There is no food source for manatees in the discharge canal, so they periodically leave the power plant and frequent seagrass beds around the Tampa Bay area.”

One of the exciting discoveries of the two-day research event was a manatee so young its fetal folds could still be seen. Four manatees in Save the Manatee Club’s adoption program frequent the Tampa Bay area, but none of them were sighted at TECO on the days the FWC staff were present. However, Higgs said that Flicker, one of the Tampa Bay adoptees, was sighted on Friday the 17th resting with over 15 other animals in a canal on the east side of Old Tampa Bay. 

Ranger Wayne Hartley checks the run at Blue Spring to see which manatees have arrived for the winter.
(Photo © Walker Stanberry )

Blue Spring
State Park

On the other side of the state and up a bit, you can find Blue Spring State Park. The park is located in Orange City, about 35 miles north of Orlando. Centered around a natural spring that maintains a constant 22 ° C (72 ° F) temperature, Blue Spring is a designated winter refuge area for manatees traveling the St. Johns River system.

Ranger Wayne Hartley tracks the manatees at the park for research purposes. By mid-November, he reported that many manatees, mostly young ones, had already made a visit to the park. But after a temperature dip on November 20th, other manatees had definitely arrived.  

“There were 95 manatees in the run this morning,” said Hartley. “The water temperature was 64 in the river and the manatees have been trooping in. Several of the Save the Manatee Club adoptees are here. Howie is here, and I saw Robin just now. Phyllis was in earlier with her calf. I didn’t see Lily, but some other staff did, and they were horrified at her scars. She doesn’t have any new ones, but her old ones are bad enough.”

At the end of November, a record 127 manatees were present for "morning roll call" in the Blue Spring run. (Photo © Walker Stanberry)

“I get confused with some of the old timers,” he continued, “but Paddy Doyle was the first manatee I recognized, and then there was Merlin. Floyd was in – he’s easy to spot because he only has half a tail. Let’s see, Philip is definitely in. We haven’t seen Whiskers yet, but he could be here. The wind makes it difficult to see. However, I’m not worried as I know the manatees aren’t going anywhere because of the cold weather.”

Other Blue Spring regulars such as Lillith, Lunatic, and Georgia were also at the park, Hartley reported. And he remarked that one manatee had come in with a badly injured tail. “I looked at him with bated breath as it was a bad one – pie-shaped all the way up to the peduncle – but it was an old scar,” he said. “It was a very young manatee and obviously one who was injured last year, but the injury has since healed.”

On a bright note, however, Hartley observed lots of newcomers. “We’ve got calves, oh my goodness, do we have calves,” he laughed. “I’m not even beginning to get them sorted yet. Lillith has a calf. Blossom has a calf. Phyllis has a calf, and Phalcon, her daughter, has a calf. Deborah and Judith also have calves. I’ve only seen Judith once, but she’s definitely got a calf. Precious, Lucille’s daughter, has a calf of her own. Precious has been hit by a boat this year, but she survived, and she’s nursing a calf, so that’s some good news to start off the season.”

Update! Ranger Wayne Hartley reports that a record 127 manatees were counted in the Blue Spring run on November 21st. In addition, Flash, Lenny, Lucille, Nick, and Margarito have all checked in at the park. And Elaine, who was a no-show last season, is back!

Judith (at right) is one of the many manatees who came to Blue Spring this winter accompanied by a calf. (Photo © Walker Stanberry)

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