“Spirit bears” (white bears, not polar bears)
Medusa spiders, which only seem to bother two people
Horses (we see at least one on-Island pre-Dharma)
Land Birds, who act as helpers, who give warnings, including the “Hurley-bird”
Fish which allow themselves to be caught, or not
Other sea creatures (invertebrates, like sea urchin)
Buzzing insects (flies, gnats - we only see them in The Barracks, IIRC)
All have powerful thematic importance (and action) in the story, far beyond “chance.”
Perhaps this is why the Island’s animals are unaffected by the Incident, are still able to reproduce, and also why they don’t overrun the Island.
Also explains the absence of rats, roaches, infestations of flies, other vermin.
IOW the Island’s ecology is NOT a real, scientifically-based ecology, but a genuine fairy-kingdom populated by spirit animals as well as other eldrich beings. (Interestingly, “eldrich” or “eldritch” literally is Old English for “the other kingdom.”)