Why have orcas never attacked humans in the wild, but other dolphins have? If interactions with orcas were as common as interactions with bottlenose dolphins, would there be incidents?
That's an interesting question!
First of all it's important to note that killer whales have shown negative behaviour/attacks towards humans in the wild. Most famously, Californian surfer Hans Kretschmer was bitten by a killer whale in 1972. The original news article is down, but he is interviewed in this more recent article.
It is probably the only known documented incident of a wild killer whale biting a human. However, quite some other, albeit less direct, cases of aggression have been reported. Antarctic killer whales have tried to tip people off ice floes, or wash them out of their boat, reported in both 1910 and 2010 coincidentally (when the Frozen Planet crew in their zodiac apparently were the target of a wave-washing attack).
Cetacean researcher Bernd Würsig was attacked in 1989 by one of the Peninsula Valdes killer whales. He was observing sea lions from 200 metres away, hoping to photograph a hunt, when a killer whale beached to grab him and only missed him by a metre. And of course there's numerous incidents of killer whale damaging boats, not just the recent ones off Iberia, but also going back several decades.
However, attacks are not nearly as numerous or physical as those documented for wild (bottlenose) dolphins. I think number of encounters certainly plays a role there. Bottlenoses can live very close to shore in warm waters, so ideal places where people bathe and swim. Bottlenoses are highly sociable but live in much looser societies, meaning solitary animals may happen more frequently, and then look to humans for companionship. I believe most attacks come from such solitary animals, that are (too) accustomed to humans. Add to that that bottlenose dolphins are quite a sexually aggressive species too. They can be boisterous and rough when demanding attention, especially with a frail human. However, bottlenoses are not the only "culprits" - through personal communication I've heard of quite some stories of other species being rough with or injuring people who swam with them, or viewed them from a boat.
Killer whales generally live in colder waters and further offshore. Small chance of meeting one when going for a swim in the shallows. It seems solitary killer whales also happen much less frequently, and when they do, they rarely end up seeking human companionship. One notable exception is of course the young killer whale Luna. He did seek out extensive human contact for a long time. I don't believe people swam with him, but there was also no documented aggression from him as far as I know. Perhaps this is due to the generally calmer nature of killer whales, but it's hard to say with just one example.
So I think it is a combination of factors. Mostly the much greater number of interaction people have with (smaller) dolphins vs killer whales. I think in part also due to differences in behaviour/levels of aggression. And maybe people also act more stupid around smaller dolphins? Because those are always portrayed as so friendly, and cute, and of course this wild animal wants a full body hug from me! While for killer whales people (hopefully) have a little more respect.
Interesting topic for sure, if anyone wants to pitch in!
