This blog was created to allow the public to follow two manatees, Rita and her calf Georgie, as scientists track them after their release back into the wild. Please return for weekly updates.
NOTES FROM THE FIELD – WEEK 4:
A rainy morning prevented Kelly Melillo (Dolphin Communication Project) and Kendria Ferguson (BMMRO) from heading out on the boat to search for Rita and Georgie, but Argos satellite locations indicated that they were recently in the harbour.
In the late afternoon, we received a call from Al (a local fisherman) saying that manatees were under his dock just a few houses down. Manatees are frequently seen here when they are in the marina. Gina and her calf, JJ has been observed resting and feeding under this dock on numerous occasions.
We have the use of an extra GPS tag from USGS to deploy on another manatee should the opportunity arise. Having data from one of the resident manatees would enable us to compare with Rita’s evolving habitat use patterns.
A prime candidate for tagging is the adult male (pictured left), who we assume by his faint scar patterns to be the original male first sighted with Gina in 2000. Tagging him would be particularly interesting because he is not seen as often as the other manatees. We think he may be the manatee that fishermen sometimes report in Andros, and tagging would help document those movements.
A pattern described by the local community is that he breeds with Gina, disappears for a few months and returns just in time for the birth of her calf. Tagging will allow us to get a better understanding of his travel patterns and areas he visits when he is not seen with the other manatees.
|Gina and her calf, JJ covered in brown algae.|
There is also a visible difference in skin color between the two males and Gina and her small calf JJ. Gina and JJ are covered in brown algae whereas both males are fairly clean with minimal algae growth. Notably, the males are often seen with remoras attached to them, which are known to reduce the amount of algae on the manatees they attach to. In Florida, the non-native suckermouth armored catfish are often seen attached to manatees and feeding on algae that grow on top of their skin (Nico et al., 2009 ).
Although these observations are speculations and require further attention, they do bring up questions of interest.
- Do remoras always associate only with particular manatees?
- Where are Gina and JJ spending most of their time when they are not seen in the marina and is this resulting in more algal growth?
Unfortunately, Kelly and Kendria were unable to tag the adult male. He remained elusive whiles we were in the water with him and the juvenile male.
Leo G. Nico, W. F. (2009 ). Interactions between non-native armored suckermouth catfish (Loricariidae:. Aquatic Invasions , 511-519.
Early morning Argos satellite locations and strong VHF radio signals indicated that Rita and Georgie were still in Great Harbour Cay harbour. We spent the early morning getting extra work done before heading out to search for the tagged ladies.
Shortly after 1pm we jumped aboard our boat and put on our manatee searching hats! After a 2 minute boat ride, we tracked our two tagged ladies just under a townhouse dock, with the two males. We quickly turned back around and tied our boat back up. With the challenge of tagging the adult male, we quietly entered the water and began to swim towards the manatees.
Sadly, we were unable to get a tag on the adult male but were happy to see Rita and Georgie socializing with the two male manatees. Both males have often been seen with Rita, suggesting mating may be in the near future. Along with Great Harbour Cay being a suitable habitat for manatees, one of the reasons Rita and Georgie were released here was to also add to the genetic diversity of the resident manatee population. A calf is typically with the mom for two years after birth. During this time they are taught where to locate food, shelter, warmth. After these two years, the mother is then ready to mate, and after 12 to 13 months within a year may have a next calf.
All four manatees remained in the marina for the rest of the evening and were last seen shortly after 6pm.
The tracking team woke up to reports of manatees being seen under a town house dock in the marina. A quick swing of the ‘H-antenna’ on our VHF field tracking receiver told us that Rita and Georgie were very close to the marina and possibly just in the harbour.
Shortly after noon, Kelly noticed the adult male swimming past the townhouses towards the eastern end of the marina leaving a trail of tail prints on the water surface. Not too long after, he swam slowly under the tracking team dock towards the western end of the marina. Travel routes under the townhouses and the marina dock is not uncommon amongst the manatees here. They understand that boats frequent the area and have opted to seek cover when traveling in and out of the marina.
The tracking team was very intrigued by his quick travel so we headed out to search for him and the tagged ladies, Rita and Georgie. This was a great chance to invite Frenchie, the island’s nurse and ‘Jane-of-all-trades’ along with us. Frenchie will be assisting in montoring Rita and Georgie in the upcoming months.
We found Rita and Georgie in the ‘T-canal’ of the harbour. Tagging data obtained from Gina in 2000 showed that she also frequently visited this canal (see map from 11-May-2012). This area is an important area for feeding, resting and possibly a freshwater resource. Historically, Berry Islands is known to have fresh water ponds; one of which was cut into during the construction of this ‘T-canal.’
Initial observation of Rita and Georgie lead us to believe that they were resting when they were sighted at the southern end of the t-canal. Manatees can spend up to a couple hours bottom resting, and during this period it is important not to disturb them. We want to limit any sort of disruption of natural behavior when observing these animals or any other mammal in the wild. For that reason, we left them shortly after we found them and went to search for the adult male.
Unfortunately, we were unable to locate the adult male but felt certain that he was still in the area.
When searching for manatees there are a few things that you should look for:
- A nose breaking the water surface to breathe.
- Fluke prints or any water disturbance (eg. Body movements).
- Bubbles! As they ascending to the water surface they may emit a few bubbles.
Although these three points may help with locating a manatee in the wild, a tracking tag attached to the animal is a great advantage!
Pulse signals emitted from their VHF tags once again indicated that Rita and Georgie were nearby which provided some downtime for us to get some work done ashore.
In the late afternoon, Kelly, Kendria, and Frenchie left the marina to search of Rita and Georgie. We couldn’t find Rita and Georgie in the harbor and thought that they may have left the harbor. To re-energize, Frenchie and Kelly took a quick snorkel in a blue hole, located in the creek just north of Bullock’s Harbour. Very little is known about this bluehole. On Hoffmans Cay, South Berry Islands there is a 600-ft inland bluehole often visited by tourists. Water clarity limited Frenchie and Kelly’s visibility but they enjoyed the brief moment of down time nevertheless!
|Photo from: http://www.aircharterbahamas.com/images/berry_islands_map.jpg|
After this moment of exploration, the tracking team continued their search for Rita and Georgie. With infrequent signals and less than ideal sea conditions, we weren’t getting a good sense of directionality from their tag signals but knew that the tagged manatees were still in the area.
Later that night, Argos locations showed that Rita and Georgie had begun their journey up north towards Cistern Cay. This would be their fourth trip up north since their release on April 19th, 2012. Based on previous trips up north, the tracking team anticipated that they will go to one of three locations: Lignum Vitae Cay, Coco Cay, or Great Stirrup Cay.
Lignum Vitae Cay is a known feeding area visited by Rita and Georgie during previous trips up north. Upon inspection, this area has an extensive turtle grass (Thalassia testudinum) beds. Turtle grass, manatee grass (Syringodium filiforme) and shoal grass (Halodule wrightii) are the three seagrass types commonly found in the Bahamas.
But instead of stopping in at Lignum Vitae Cay, Rita and Georgie continued to the southern side of Great Stirrup Cay. This area also has lots of seagrass, which may be another attraction for them to this area. After a quick trip around the western end of Great Stirrup and along the northern side of the island, they continued south along the eastern side of Great Harbour Cay. This trip is familiar to Rita and Georgie as they took a very similar trip within their first week of release.
Early morning satellite locations showed that Rita and Georgie had continued south along the eastern side of Great Harbour Cay, pass Petit Cay, and towards the shallow banks off the western side of Ambergris Cays. By 4:30pm that afternoon, they had explored the shallow banks off the western side of Amerbergis Cays and headed southeast to Holmes Cay.
There was a shift in the tracking team today!
Kelly began her trip back to Bimini and William Bonner a college student and BMMRO volunteer returned to Berry Islands to assist Kendria. William spent some time in the Berry Islands prior to Rita and Georgie’s release. During this time he recorded sightings of manatees and assisted in outreach efforts with the local fishermen.
At 6:30am, Argos locations showed that Rita and Georgie were at Holmes Cay. Bad weather prevented Kendria and William from organizing a trip south, instead Rita and Georgie’s movements were monitored via Argos satellite data.
Locations received shortly after 2pm showed that Rita and Georgie were off Little Harbour Cay which is just over 10 nautical miles south of Great Harbour Cay. This is the first time that Rita and Georgie are exploring the southern islands of Berry Islands. On a previous visit south, they quickly turned around near Ambergris Cays and made a 10 mile trip back north to Great Harbour Cay. Their movements will be monitored closely throughout the night to see how they navigate in this unfamiliar territory!
Argos locations received shortly after 6am showed that Rita and Georgie were still off of Little Harbour Cay. Throughout the day, they would continue to explore this area and venture further south towards Bonds Cay.
The resident manatees of Great Harbour Cay have been sighted as south as Chub Cay. Although Rita and Georgie didn’t travel this far, it is refreshing to see them explore other areas frequently visited by the other manatees.
Today, Willie and Kendria welcomed one of BMMRO’s board members, Beth Cook and her husband to Great Harbour Cay. Beth is a Bahamian from Nassau who has recently relocated to Abaco after 30 years in the US raising a family. She has a keen interest in the marine environment and is excited to become involved in local conservation. Beth joined BMMRO's board in 2010.
At 6:19am, Argos locations showed that Rita and Georgie were heading north towards Ambergris Cays. On a previous trip south, Rita and Georgie took ‘the channel’ cut west of Ambergris Cays and headed back north into the harbour of Great Harbour Cay. Now within familiar territory, Rita and Georgie continued north pass Sharks Creek. Initially, they went pass the harbour entrance but they turned around and headed into the harbour.
At 5pm, Rita and Georgie were observed feeding in the harbour along with both males. It is still unknown whether the two males traveled with Rita and Georgie around Great Harbour Cay and towards the southern islands.
In five days, Rita and Georgie had traveled over 70 miles around Great Harbour Cay.
A very long journey with a very happy ending!
A plot of the locations of Rita and Georgie via Argos satellite shows their fourth weeks' movement around Great Harbour Cay; arrows indicate direction of travel from Great Harbour Cay harbour to the southern islands of Berry Islands and back north to Great Harbour Cay harbour.