If male and female birds are about the same size and have plain coloration, the scientist can conclude that sexual selection is likely not a major factor in the species’ evolution. In many bird species, bright male plumage evolves to attract mates, but plain, monomorphic coloring suggests other pressures are at play. For example, subdued colors may provide better camouflage from predators, and smaller size may help with predator avoidance or foraging. Further study would be needed to determine which evolutionary factors are most important.