Blue Whale Mating 101: How Often Do Blue Whales Mate?

how often do blue whales mate

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Mating plays an extremely important role in the life of all members of the animal kingdom.

Different species carry out mating rituals that are as diverse and unique as they are interesting. So how does the mating ritual of the largest animal to ever exist play out? 

How long does it take female blue whales to produce a calf that will be born weighing 2.5 tonnes / 2.7 tons and measuring 8 m / 26.3 feet? How often do blue whales mate? What goes into the mating process of this solitary mammal? 

Let’s dive right in (pun intended) and learn more about blue whale mating and everything that goes into it. 

How Do Blue Whales Actually Mate?

Little is known about mating in blue whales as, even with their enormous size, it is not easy finding them in the vastness of the ocean.

These whales also tend to be shyer than other whale species and will actively avoid areas with too many boats or people. 

So how do blue whales actually mate? Scientists have made assumptions based on the mating behavior of other closely related whale species but the mating act between two blue whales has never been recorded. 

What is known is that, unlike other baleen whales, the blue whale is solitary during most of the year and will start to pair up a few weeks before the breeding season begins.

You could call it a “dating period” of sorts. 

During this time a male will start following a female around for several weeks, occasionally warding off other male suitors that show up, in what is believed to be part of his courtship ritual.

When the female has chosen a male, the two will engage in a kind of dance swimming around each other and rolling together.

The pair will then start descending into the ocean’s abyss while still communicating via vocalizations and coordinated movements. 

After some time the pair of blue whales will start swimming back up towards the surface with the male penetrating the female.

After mating takes place the pair of blue whales go their separate ways and no lasting bonds between them will be formed. 

How Often Do Blue Whales Mate?

Blue whales reach sexual maturity between the ages of 5 – 15, after which males will mate every year during the length of the breeding season and females will do so every 2 to 3 years.

These creatures are polygynous, meaning they have more than one partner throughout each breeding season.

In fact, during this time both sexes will mate with as many partners as they can to increase the likelihood of producing offspring.  

Blue whale mating occurs in warmer, tropical waters close to the equator.

The breeding season extends for about 5 months, from fall until winter, after which they start swimming toward the poles where they spend spring and summer. 

How Often Do Blue Whales Give Birth?

Blue whales give birth every 2 – 3 years to a single calf. 

Remember I told you that while the male mates every year the female only does it every 2 to 3 years?

This gap is spent carrying the pregnancy to term, which takes 11 – 12 months and subsequently caring for her calf which will wean when it reaches 8 months of age.

If a female blue whale doesn’t get pregnant or miscarries during 1 season she will mate again the following year.

The longest-lasting social bond witnessed in this species is the one between a mother and her calf which can extend for a few months, or even a few years, past the age of weaning. 

More On Blue Whales Mating

As I mentioned before there is still a lot to learn about the reproductive lives of the largest animal on earth but scientists have come to conclusions by studying closely related species that provide some insight into what takes place in blue whale reproduction.

Now that we know the basics of mating in blue whales it’s time I share some pretty amazing random facts about it as there is a lot more to unpack when it comes to the mating process of these gentle giants.

Let’s start by answering a question I had always been curious about and you probably are too; Can blue whales have twins?

Could it be possible that the largest animal on the planet could deliver more than one  2.5 metric ton calf?

Twins are a rare occurrence in baleen whales but do happen.

However, it is very likely that when they do, one or both offspring perish due to the limited milk supply of the mother as just one calf requires around 220 kg / 485 lbs. of milk per day. 

And now a fact that I personally find pretty amazing: There are documented cases of hybridization between blue whales and fin whales! Even cooler?

These hybrids are fertile. There are a few living individuals that are a product of interbreeding in Canada and Portugal. 

Other documented hybrids have been discovered thanks to genetic testing done on whales that have been caught by whaling ships and the analysis of whale meat samples from some Japanese markets.

There is also knowledge of at least one blue-humpback whale hybrid.

Final Thoughts

To me, it is absolutely mind-blowing how there is so much that remains unknown about the largest animal to ever live.

The sheer fact that not a single event of blue whale mating has ever been documented speaks volumes about the vastness of our oceans and how many secrets it keeps. 

When it comes to how blue whales mate what is known is that as mammals they reproduce sexually, and they prefer to do it in warmer waters, it is also known that both sexes have multiple partners per breeding season; everything else still remains a mystery.

However, you and I can rest assured that blue whales are indeed mating.

Luckily, their population has been growing at a stable rate of 7 – 8% per year for the last decade, slowly but surely recovering from being on the brink of extinction during the 1900s whaling craze.