This is something I’ve wondered about for awhile, prompted initially by a couple of encounters (before I was taking footage, unfortunately) of animals that seemed intermediate between California and Steller sea lions.
I’m familiar with some cases of hybridization between different species of otariids, but I can’t find much of anything online about these two species specifically, aside from descriptions of an incident in the 1990’s involving one individual suspected of being a hybrid. Here’s a link to a 1996 article about this in the LA Times, if you’re interested: [https://www.latimes.com/archives/la-xpm-1996-06-02-mn-11105-story.html]
Where the ranges of the two species overlap, they often haul out together - at least outside of the breeding season. I have observed a lot of interactions between Steller pups and California bulls, with the pups often running right over the bulls, or napping on top of them, and - in every case - I’ve been struck by how easy-going the bulls are toward the pups. I’ve also witnessed instances in mixed-species haul-outs where an SSL bull is being aggressive and pushing around CSL bulls, seemingly prompting female Stellers to intervene and chase off the male of their own species…
Anecdotes aside. Given the degree of social interaction between the two species, the fact that the southernmost part of the SSL breeding range overlaps with the CSL breeding range, and the existence of hybrids between other pairs of otariid species, it is tempting to think there must be some hybridization happening…
If anybody has any insight or thoughts about this, feel free to share!