In the warm waters of the tropics,
a female humpback is courted by amorous males intent on mating.
But which of them will succeed?
Will she choose the patient suitor?
One of the three show-offs?
Will she become weak at the fins when the male starts singing?
Or does she have other priorities on her list anyway?
Each year, from July to October, humpback whales pass by the Cook Islands
as they migrate from their cold feeding grounds near Antarctica
to the warmer waters where they will mate and give birth.
This female delivered her calf on the journey.
Now less than a month old, the calf is totally reliant on its mother
for food and protection.
Every day, it will drink around 500 liters of fat rich milk.
In a year, it will have doubled in length.
The mother won't feed herself for about 3 months
while nursing her calf in these warm waters
because to leave in search of food would expose the youngster to predators.
A good store of blubber will see her through.
She conserves her energy by taking fewer breaths and, most importantly,
abstaining from sexual activity.
But now she has an uninvited visitor.
A male companion who wants to mate.
The female dwarfs the male.
One study shows that males prefer bigger females.
The larger she is, the better chance that his offspring will survive.
She ignores him.
Instead, she rests with her calf tucked safely beneath her fin.
Her calf is the only whale that matters here.
The youngster needs to breathe at shorter intervals than its mother.
Mature whales usually come to the surface and breathe every 10 minutes or so.
But calves have to breathe every 3 to 5 minutes.
With a little help, the calf rises to the surface alone to blow and inhale,
before diving back down to its mother.
Still, the escort patiently waits for some sign of interest.
There are other less chivalrous suitors on the way.
Three males high on hormones.
Their formidable displays are far from the gentle behavior
we've come to expect from humpbacks.
The males stay close to the surface to oxygenate their blood
as they thrash their tails in a show of dominance and strength.
Males can die in these encounters,
females can be injured
and calves can drown.
But it's an anticlimax.
The female has had enough unwanted attention.
She's moved on to more peaceful waters with her calf
leaving the hormone-charged males and the polite escort in her wake.
Some females haven't even made the journey north to the tropics.
Those that give birth before the annual migration have stayed
in the cold Southern Ocean
With so many ineligible partners, the males around Rarotonga outnumber the females.
Competition is fierce.
But it isn't always about who has the biggest tail.
The rejected escort has joined forces with the 3 males.
They won't waste any more energy on the pursuit of disinterested females.
Time to employ a different tactic.
They'll lure the females to them by forming a quartet to sing whale songs.
The sounds of the male humpback whale chorus vibrate through the warm waters.
No more violent displays of dominance, singing is a much gentler pursuit.
But what purpose did these songs really serve?
The most popular theory is that male humpback whales sing to attract mates
during breeding season.
But a recent study shows that they also sing outside of these times.
Humpback songs have been recorded in Arctic feeding grounds and during migration
There may be more than one reason why humpbacks sing.
Some scientists even speculate that the songs generate sonar.
Rather than to attract females,
the whales might seem to actively explore the world around them
to find other whales and monitor their movements
But for now,
whether the male humpback whales are singing for sex or sonar remains a mystery.
We know so little about them.
We've never even seen a humpback whale mate.
Does it matter?
Perhaps the most important thing is that, whatever means they use,
when the humpbacks reach warmer waters after their long migration,
they will find mates and deliver the next generation.
Don't forget to check out our clever humpback whale video
where we followed a hungry female into an Alaskan salmon hatchery
and please do consider to subscribe.