It’s a Female Dolphin’s World Why Less Males Here?

You’re in the jungle, observing two male gorillas when, all of a sudden, a battle ensues. These big boys will fight each other voraciously until one is defeated and retreats away from the others. There’s a winner and he is the dominant male. He has earned the right to mate with the females.

This type of battling happens throughout the animal kingdom, creating dominant males in a variety of species globally. Whereby many different animals have a singular male as “king of the hill” it‘s a little more intricate in our local dolphin society.

The 10,000 Islands Dolphin Study Project, the only dolphin study program in Southwest Florida, has documented that there are 15 adult males and 39 adult females in the residential bottlenose population of north Marco Island, but it also includes calves (typically under three years old) still next to a mom’s side and another segment of youngsters that have not yet reached maturity known as sub-adults.

Why so many females and just a handful of males? The answer lies in the opportunity of a select number of males who dominate the mating rights.

The “kings of the hill” in our dolphin society consist of six males - six of the 15 adults who are at the dominant positions.

Unlike other sectors of the animal world where one stallion controls a herd of wild horses, a walrus fights for that top spot, and on and on, these six males have a unique pairing system that helps them be the best.

Two males will form an alliance, a Male Pair Bond, when they reach maturity at about 12 years old. They are still growing but they will hunt for food together, socialize strongly with each other, and also chase the females together. Our six top males, three Male Pair Bonds have been ruling the mating game for more than 15 years or longer!

One Pair Bond will actually follow a mature female who is ready to mate so that they can take advantage of that opportunity. Having two big boys following that female will actually deter the younger males from approaching. This bonded pair might follow the female for weeks and then move on to another “eligible bachelorette.”

Our team witnessed a very interesting event just a few months ago. Three females were traveling along the Marco River when two younger males, Jayson and Kona, started to approach them. From a distance, we noticed two more dolphins coming toward the group. Dominant Pair Bond Bangle and Finch were on their way to assert their position in the hierarchy. There was a lot of white water, thrashing, and dolphin fins rolling over each other. In a matter of one minute or so, Jayson and Kona were moving away from the females. Bangle and Finch, a Pair Bond of 15 years or more, secured the rights as ‘Kings of the Hill” for another day.

Jayson and Kona would have to wait for another opportunity. They are mature males but young and inexperienced, not able to compete for a spot in the top six category. They have some physical growing to do before they are ready for the big battles. They are forming that Pair Bond but will have to wait their turn to compete with the big boys. This could take years.

We have also witnessed some of the females that seem to seek out these dominant males. Our birthing season in this sector of the world is predominantly September, October, and November. The pregnancy period for a female is 12 months, which means that our primary mating season, that time when females are ovulating is now at hand.

Documenting our sightings on a daily basis, we have found that certain females who are experienced moms tend to search for specific dominant males when they want to conceive. One such case is an adult female named Halfway. A mom of seven offspring, she will be seen with Male Pair Bond Hatchet and Capri, two of the largest males in our area, when she wants to become pregnant. These two males are likely the fathers of Halfway’s offspring. 

It makes sense that the female will look for the strongest males to father their offspring to ensure the best bloodline for these new young, just like other sectors of the animal kingdom. 

Back to the ratio of 15 adult males and 39 adult females, where do the young males go that have left their mom’s side at age three or four? Research indicates that the adult males will recognize the younger males as potential competition when these youngsters mature and will chase them from the area. This assures the top males that they can maintain their mating status with the local females.

However, some of the young males do stay in the area. Could they possibly be the offspring of the adult males? Do these big boys actually recognize the younger boys are their offspring? The jury is still out on that matter, pending research and more data collection by the team.

We mentioned that Jayson and Kona have formed that alliance but are still growing and will need some time to be among the top males. We do have two males, Simon and El, who are now 17 years of age or more and are just as big as some of those top six males. There could be a change in those top six in the next few years, with Simon and El showing more dominance and some of the “Kings of the Hill” getting older - Captain Jack, being one of them, is likely in his 50s or 60s.

The adult males will be busy over the next few months as females ovulate and want to become pregnant. These boys were very busy at this time last year, as we expect to see about 10 to 15 new births in the next 30 to 90 days.

Stay tuned for more updates here at Coastal Breeze News. You can also follow progress on our Facebook page The Dolphin Explorer, Marco Island.