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Frisky dolphins amazing in warmer weather

Phil Coulthard, Dolphin Discovery CentreSouth Western Times

Summer holidays may have ended months ago, but the persistent warm water along our coast continues to fuel the fire for our local dolphin population.

The past few days have been particularly intense, with countless male alliance groups travelling to Koombana Bay in search of the last of the available females to mate with.

Monday morning alone saw at least 50 male dolphins in three separate groups competing for the attention of just a few local females.

April has always been seen as the last month of suitable environmental conditions for females to fall pregnant, so those yet to conceive are pursued with great enthusiasm (or would that be great desperation?).

Either way, the action is spectacular and offers us all the perfect opportunity to observe true dolphin behaviour in the wild these school holidays.

For the benefit of those who are not regular readers of this column, the local dolphin breeding season peaks when the water temperature falls to its optimum range of 23C.

Why they wait for the temperature to fall to this mark is all about calf survivorship and the ideal conditions the calf requires to thrive once born.

In Koombana Bay that time appears to be in March and April, when the drop in water temperature to 23C coincides with perfect weather conditions, a decreased risk of shark presence and an increase in the amount of food available for the new mum.

Considering the dolphin gestation period is 12 months, it also makes a lot of sense for the majority of mating behaviour to occur at this time and leaves us all completely amazed and a little exhausted whenever we are out on the water.

Scripted like a best-selling novel, male dolphins live a committed and structured life based around what scientists call an alliance.

Like kids in a school yard, as the young males grow up they form strong bonds with other boys their own age who share similar physical abilities.

Incredibly, research has also found alliance members are often genetically related, either as brothers or cousins.

The importance of this fact may be of little consequence at first, but as the males enter adulthood and become sexually reproductive (about 12 years of age), their preference to share the female within the group means it is critical for each member to have similar bloodlines.

In comparison to most mammal species such a strategy is rare, but for the dolphins of Koombana Bay it has proven to be successful.

At last count more than 10 new baby dolphins had been observed this breeding season and another five to 10 are expected to be born before the end of April.

That said, the natural mortality rate for these little guys is still over 40 per cent due to poor parenting, malnutrition, predation and human impact.

Our actions can and do add to the overall mortality rate of these animals, so every effort we make to minimise our impacts on the dolphins at this time is critical.

Avoid getting too close to the dolphins and allow them to plenty of space to swim freely, particularly those maternal groups close to The Cut.

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