Young jays commonly collect brightly colored objects like bottle caps and pieces of aluminum foil and carry them about for awhile. Sometimes they try to peck open such objects, or they will use them as platforms and simply sit atop them until they get bored with the new-found curio. As noisy and aggressive as they can be, blue jays are very secretive during the nesting season. They pick nesting sites in thick cover and take circuitous routes through tangles of vines and shrubs to reach their nests. They prefer coniferous trees like pines and cedars for nesting sites when such trees are available.
Blue jays are monogamous, meaning pairs bond and remain together for life.
The male courts the female by feeding her constantly and continues to do so while the female incubates four to six brown-spotted, greenish eggs. Both sexes have the same appearance, and young blue jays are gray-colored until they get their adult feathers. While blue jays are noticeable all year, they are most obvious in the fall when they form loose-knit groups and forage for food as they roam the countryside. As aggressive as the blue jay is, it is easy prey for hawks and owls when in the open, because it is a slow flier when compared to other perching birds. Its large size, about 12 inches from bill to tip of tail, also makes it an easy target for avian predators.