A photographer and a scientist may have caught the first ever video of a “heat run” between blue whales.
A whale with her calf [Photo by Frank Brennan/Dana Wharf Whale Watch]
A heat run is when a male of a certain species chases down a female in an attempt to mate. Humpback whales have well-documented instances of heat runs, but not blue whales. Heat runs among humpback whales, in fact, can get quite violent. Several males would be in competition with each other in order to mate with the female they're chasing. Of course, the rival males would need to make sure that they emerge the victor. A 2009 BBC Earth video clip shows male humpback whales walloping each other with their tail flukes, even going as far as breaching through the water and crash landing on each other.
Those are humpback whales, however. Though the blue whale is the largest animal on Earth, we don't really know much about them. For example, there is no known footage of blue whales in a heat run.
Watch the video footage here.
Photo by Flip Nicklin, National Geographic Creative
Whale photographer Patrick Dykstra and blue whale scientist Howard Martenstyn were able to film two blue whales swimming off the coast of Sri Lanka. Because we don't actually know what a heat run between blue whales looks like, scientists aren't sure if this was indeed a heat run. However, it's highly possible that it was.
Blue whales are sexually dimorphic. This means that the males and females of the species have noticeably distinct physical characteristics. For example, you'd generally be able to tell if a person is male or female based on the way they look. In blue whales, females tend to be larger than the males. One of the whales in the footage—the one being chased—is larger than the whale doing the chasing.
According to Dykstra, the larger female whale was also displaying atypical behavior toward her pursuer. “This female is rolling over on her side and flipping upside down,” said Dykstra. He ays that this behavior was likely meant to entice or engage the pursuing male.
Now, you may wondering: was the male successful in his pursuit? Unfortunately, much to the disappointment of the observers, they were unable to see if this courtship ritual culminated in mating.
Photo by Jimmy Mann
Dykstra, Martenstyn, and a team of researchers spent several hours a day for several days watching the two whales. According to Dykstra, he and the team had to return to their base when night fell. Thus, they weren't able to continue observing the two whales.
Still, their footage is significant. The sheer size of blue whales means that they spend most of their time feeding on krill. Thus, seeing them spend so much time and energy on something that isn't feeding is quite rare.
Marine ecologist Leigh Torres, however, cautions against conclusions that the whales were engaged in a mating ritual. According to Torres, whales have been observed to engage in “racing” that wasn't connected to mating. Blue whales are also known to sometimes travel in pairs. Thus, it's possible that the footage wasn't showing a heat run. Then again, it's also possible that it was.
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