Since its inception in February 2006, the 10,000 Island Dolphin Project has monitored the abundance, distribution, movement, range, association patterns and behavior of the bottlenose dolphins on the north end of Marco Island, Florida. This is done on board the vessel known as Dolphin Explorer. The study depends on public funding as guests join the survey team for education about the area cetaceans as well as information on the area ecosystems.
The dolphins are not captured and tagged, instead they are identified by the markings on their dorsal fins, causing zero stress to these mammals. Markings are created as one dolphin rakes its teeth across the other’s dorsal fins. Other markings could also be caused by incidents with boat propellers or injuries.
From January 1st through June 30th of this year, there have been 158 excursions on board the Dolphin Explorer to find and identify local dolphins. During this time, 1,475 individual dolphin surveys have been recorded over 158 trips for an average of 9.33 dolphins per trip. There are just over 100 resident dolphins in the survey area so, naturally, there have been multiple sightings of many individuals in the last 6 months.
Of primary concern during this time would be the development of young calves.
Birthing season in this region tends to be late August through mid-November. In the Fall of 2019, there were 9 new calves documented with 6 currently surviving. Loss of life could be attributed to shark attacks or infanticide by other male dolphins. The number of deaths is high compared to many other years. In the Fall of 2018, there were 10 calves born and 9 are still alive. On average over the past decade, about 75-80% of calves survive past their 3rd birthday.
With birthing season beginning at the end of next quarter, one of our calves has already left its mother’s side. The young will typically stay with mom for 3 to 4 years in our region. It is not uncommon to see some of these leave the adult female’s side at 32 to 34 months old. One of those young, Jordan, has been documented twice very recently without its mother, Jing Jing, anywhere in sight.
This could be an indication that Jing Jing is expecting a new calf. Time will tell if this is the case. There are several other young reaching their 3rd birthday this Fall and we will note if this pattern continues.
We have also documented that one of our females, Nibbles, has traveled from her normal resident grounds to an area where she has given birth in the past. We have five sightings of Nibbles in this area since late May. Her calf, Popcorn, made that journey with her but has been seen away from mom on two of those sightings.
Popcorn turns 4–years–old in a few months. Nibbles’ journey from her usual residence to the birthing area is about 6-8 miles. She will give birth, raise her newborn in that area for a few months before returning to her living area.
Adult female Sydney was raising a calf named Nemo. A curvature in the spine was noted about Nemo at a very early age and concerns about its ability to feed on its own were being monitored. Unfortunately, Nemo has not been seen for several months and is presumed deceased. The calf was not yet 3–years–old.
All of our adult males have been seen on a regular basis, as have the majority of our sub-adults, those dolphins old enough to be away from mother’s side but not yet reached full maturity.
Our survey will continue, and reports will be published quarterly as usual. If you have any questions regarding the content herein, please contact Bob McConville at 239-642-6899 or email firstname.lastname@example.org.
This report was prepared by Florida Master Naturalist by Bob McConville who also serves as a Naturalist on board the Dolphin Explorer.