During a recent trip in the Sea of Cortez, photographer Mike Nulty had a chance encounter with a traveling trio of sperm whales.
While we can understand assumptions that these three whales are a family unit, Canadian biologist Shane Gero, founder of the Dominica Sperm Whale Project, explains that this is not likely the case. For starters, it is incredibly rare to witness a mature male sperm whale escorting a calf – especially one as small as this youngster. The adult whales in Nulty's clip, then, are almost certainly both female.
"It's easy to view this from a human standpoint: that we're seeing mom and dad and baby," says Gero. "Male sperm whales come into families to mate, then leave, and may never see their offspring again – this is true for many animal dads." In fact, Gero and his colleagues have only seen male and baby sperm whales cruise together in cases where the large male is a known older sibling of the calf.
That said, it’s extremely difficult to determine the sex of a sperm whale from aerial footage alone. In the unlikely event that one of these particular animals is male, it is probably either a subadult who hasn't yet left his family to pursue mating rights, or a small adult male consorting with the baby's escort.
Whether or not this calf is accompanied by its mother is also hard to pin down with confidence. The female closest to the calf could rather be a babysitter, as sperm whales are known to look after young pod members whose mothers are off diving and hunting.
Like the rest of their leviathan kin, these animals are extremely intelligent and display a wide range of complex social behaviours. Despite decades of research, scientists are just cracking the surface on sperm whale pod dynamics.
A recent study conducted in the region showed that sperm whales around the Baja Peninsula spend about 30 percent of their time resting near the surface and socialising together. When it comes time to find food, however, each whale tends to go its own way.
"We are now learning things about sperm whales that we just didn’t have access to before,” says lead author Ladd Irvine, a researcher with Oregon State University. "Unlike many other terrestrial and marine mammals that form social [hunting] groups, sperm whales seem to prefer foraging as individuals. They stagger both the starting time and the depths of their dives."
Little is known about exactly when, why, and where the whales link up. Back in Dominica, Gero and his team have observed one rogue male who appears to have taken a liking to a particular family: he's visited three times in the past 14 years.
"It could be two things," postulates Gero. "He really likes the females in that family – and they like him – so he is successful in breeding with them when he is in the Caribbean. Or, he is someone’s son back to visit his family." Without a genetic sample from the male, though, it's tough to say with certainty.
For Nulty and his colleagues, who filmed the recent encounter in Bahía de Los Ángeles, the sperm whales were a welcomed surprise. The calf even came in to investigate their boat while it was drifting nearby.
"The last thing I expected to see was this," he says. "Our boat captain, Pancho Verdugo, had never seen a baby sperm whale, despite living in the area for over 40 years. It was amazing!"
Nulty emphasizes that the vessel was in full idle during this encounter, and that everyone on board kept a respectful distance when the whales surfaced right beside them.
Sperm whales are protected across much of their range, and it's important to give them a wide berth at all times. In the US, approaching a sperm whale intentionally can land you a hefty fine, and in Mexico, approaching within 60 metres is prohibited. For this reason, it's critical that boaters are mindful during any surprise encounters.
"The baby was in touching distance, but no one gave it a pet," says Nulty. "I was totally blown away."
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Top header image: Bernard Spragg. NZ/Flickr
Whales and Dolphins
Whales and Dolphins
Oceans
