The consistency in overall body color between male and female Mississippi Kites is a notable characteristic. Both sexes display a uniform grayish plumage with subtle variations that do not differentiate them based on gender. This uniformity simplifies identification in the field, as bird watchers and ornithologists can rely on the coloration to assess the species without needing to consider sexual dimorphism.
In contrast, while the size of the beak, length of the tail, and wingspan can vary slightly between males and females, these differences are not as pronounced as the overall body color consistency. Males typically have slightly smaller features, but the overlap in size means it’s not a reliable way to distinguish between the sexes. Thus, the overall body color remains the most reliable characteristic that does not vary between male and female Mississippi Kites, making it the correct answer.