We need to know why these animals were still able to proliferate despite high levels of radiation. This doesn’t offer an explanation for that peculiar phenomenon.

The stimulus tells us that wildlife populations generally have high levels of radiation. Even if some migratory species have lower radiation levels, that doesn't explain the wildlife boom overall.

All this says is that lots of wildlife populations were likely affected by the radiation. We still don't know why their populations expanded.

We already know that the animals are irradiated, and explicitly saying that some of the radiation suppresses fertility makes the population expansion more confusing, not less. This doesn't resolve anything.

Though radiation may be a threat, wildlife populations were overall safer after Chernobyl. Humans had to leave, leading to a larger habitat with no hunters. This explains why wildlife populations increased.