It's possible that this question is better suited for stack overflow, but I think the ecologists on this site might be better equipped to answer it.

I'm trying to study two geographically-isolated populations of the same species. Inspecting the distributions, I see that both are bimodal (there's some seasonality to their occurrence), but the peaks in one population are much higher and much narrower (i.e., the variance of the local peaks is smaller).

What sort of statistical test would be appropriate to determine whether these differences are significant?