The scenario described involves both brightly colored and very dull males having higher survival rates, while males of intermediate coloring do not thrive as well. This suggests that the population is experiencing disruptive selection, which favors extreme phenotypes (the brightly colored and the dull males) over intermediate phenotypes.
Based on this understanding, the most accurate statement regarding the proportion of males of intermediate coloring would be:
Disruptive; males of intermediate coloring make up a small part of the population.