The antonyms for the word "most migrative" could vary depending on how we interpret the term. If we take it to mean "tending to migrate the least," some possible antonyms might include "sedentary," "stationary," "rooted," or "fixed." These words imply a lack of movement, indicating that something or someone is staying in one place for an extended period.
Alternatively, if we take the term to mean "not migratory at all," other antonyms could include "non-migratory," "residential," "settled," or "unchanging." These words indicate a stable state or an absence of movement, suggesting that the subject in question is unlikely to relocate, even temporarily.