The boys are back in town ... for romance

Phil CoulthardSouth Western Times

With the dolphin numbers in Koombana Bay continuing to increase throughout February in response to the peak breeding season, now would be the perfect time to get familiar with the life of the male bottlenose dolphin.

Unlike the females who spend the majority of their year living within the protected waters of the bay looking after their babies, the males are rarely seen in the shallow local areas outside of the warm summer months.

Preferring to stay well away from the female groups for the majority of the year, the boys pass the time cruising the warmer, more productive waters further offshore in their small groups.

It is only when the water temperature hits 23C that their daily routine changes and they return to the bay in search of the reproductive females who are ready to fall pregnant.

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Unlike most mammal species, male dolphins live a committed and structured life based around what scientists call an “alliance”.

Like kids in a school yard, the young males are introduced to each other by their mums at an early age and grow up forming strong bonds that will often last a lifetime.

Incredibly, genetic researchers have also discovered that alliance members are often genetically related so the female dolphins play a significant role in establishing suitable alliance membership’s right from the day the boys are born.

The importance of this fact may be of little consequence at first, however as the males enter adulthood and become sexually mature (approximately 12 years of age), their preference to share the female within the group means that it is critical for each alliance member to not only be physically capable of contributing, but for all members to offer a unified paternal signature.

Dolphins swimming in Koombanna Bay off Bunbury.
Camera IconDolphins swimming in Koombanna Bay off Bunbury. Credit: by David Bailey

Their success as an active breeding alliance also appears to increase with age as they strengthen their position within the male alliance hierarchy.

The past three weeks have been particularly exciting with up to five male alliance groups spotted among the females at any one time.

Creating what we refer to as “super groups”, these male alliances have a tendency to herd female groups into protected areas, often forming dolphin groups in excess of 50 individuals.

Bunbury Dolphin Discovery Centre marine biologist Phil Coulthard with one of the friendly dolphins that come into the Koombana Bay shore.
Camera IconBunbury Dolphin Discovery Centre marine biologist Phil Coulthard with one of the friendly dolphins that come into the Koombana Bay shore. Credit: Jeff Henderson / WA News

It is not uncommon to see these groups in front of the Cut where the males create significant tension and uncertainty due to their aggressive behaviours and screaming vocalisations.

What may appear to be playful behaviour at first, most often ends in a rush of surface attacks and full body leaps with target dolphins trying their best to avoid group separation and physical injury.

In between these aggressive bursts of energy, the boys will settle for strategic positioning amongst the female groups patiently waiting for their opportunity.

Nemo and her dolphin calf - the first born in Koombana Bay for 2017.
Camera IconNemo and her dolphin calf - the first born in Koombana Bay for 2017. Credit: Dolphin Discovery Centre

Ultimately the females will decide when and where they are ready for male company so they boys are now working overtime to present themselves as suitable mates and win over as many females as possible throughout February and March.

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