As if giving birth was not hard enough, when you are trying to push a 1.5-tons baby out of your womb, having to deal with hormone-triggered males adds another level of stress to a humpback whale in labor.
A new study published this September detailed six previously un-published humpback whale birth events. In most cases, the humpback mom was surrounded by other “escorts,” aka. other adult whales keeping close to her at all times. Having escorts during labor can be a good thing for toothed whale species, like killer whales, sperm whales, or belugas. They are there to emotionally help the mom give birth and take care of the newborn. However, things are different for humpback whales. In their case, the escorts are usually males trying to mate with them at any cost.
She’s just not into you…
Alright, alright. Being a young humpback male is hard. And having to compete with plenty of other males is tough. For many reasons, the amount of males on breeding grounds is higher than the number of females, so male competition gets really intense. As a result, males found a way to secure a potential mate. They will literally stick to one female at all times, hoping to pass on their genes to the next generation. Sometimes, multiple males escort one female, and the harsh competition can lead to aggressive behavior between the males.
Although males usually choose a female without a calf, they will not hesitate to escort a mom/calf pair, hoping to mate with the mother. Scientists reported that female humpback whales can ovulate soon after parturition, causing them to be biologically “available,” even though they are nursing their newborns. It is not uncommon to see young calves suffer aggressive behavior from males trying to access their mothers.
Harassing a female during and after birth
So why would males harass a female in the middle of giving birth?! Scientists believe a reason behind this harassing behavior of males could be the release of hormones by the female in labor. They observed males put their rostrum (nose) close to the female’s genital region, which may be a way to “scent” the female’s hormones. Ransome et al. suggested that the hormonal fluctuation before and during birth might explain those males’ behavior.
Some males in the reported birth events harassed the mom during labor and even sometimes even after the calf was born. This aggressive behavior pushed mothers to “abandon” her baby for a couple of minutes. Calves need their mothers’ assistance in the first minutes of their life, mainly to stay afloat. The females usually support them on their rostrum so they can breathe. At times, escorts can be so persistent that calves will fall from their moms’ rostrums, which causes a lot of stress to both the newborns and the moms.
The benefit of a well-behaved escort
Although escorts can be rough and seriously way over the line when it comes to consent, they can have one benefit. Given that the male is respectful and keeps its distance, its presence can discourage not only aggressive males but also predators. A newborn whale is a prime target for hungry predators. Killer whales, for example, have been witnessed hunting (successfully) humpback calves. Experts in Hawaii or Mexico think humpback whale calves are common prey for killer whales and false killer whales. Sharks can also go after newborns. Therefore, having a knight in shining armor can help against such attacks, and humpback females usually tolerate the presence of a respectful male.
Humpback whale giving birth alone?
Even though escorts were present in most reported cases, the authors of the study also noted that some humpback females have given birth on their own. The authors pointed out that maybe we just witness more births with escorts because they are easier to spot from a boat (with multiple blows). Thus, there is no real way to know the percentage of birth events that happen with escorts vs. without them. Maybe future research will bring us more information on humpback whale escorts and birth events However, one thing remains true: if you are not helping mommy and baby, leave them alone!
For further reading, click on the study by Ransome and her colleagues. I would also like to warmly thank Gavin Penfold from Birds Eye View for providing the amazing photos.
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