The distinction between male and female seagulls is not readily apparent to the naked eye. The only significant difference is that male seagulls have richer plumage than female seagulls. Due to its subtlety, however, people are frequently unable of detecting this distinction.
Although the distinction between male and female seagulls is not readily apparent to people, seagulls are able to tell them apart immediately. The human eye has three cones that detect red, green, and blue, whereas the eyes of seagulls have four cones that sense additional hues. In comparison, the eye of the seagull has four cones. The fourth cone gives seagulls the ability to perceive infrared colours, which humans cannot. As a result of this disparity, male seagulls look much brighter than their female counterparts.
Species in which only the female raises the young tend to have the most variance in coloration. In such instances, the brighter plumage attracts predators to the males, so keeping them away from the female and her offspring. However, they are extremely attentive parents. Both the male and female seagulls take turns incubating the eggs and feeding the chicks after they hatch.