|The Northern Mockingbird builds a twig nest in a dense shrub or tree, which it aggressively defends against other birds and animals, including humans. When a predator is persistent, Mockingbirds from neighboring territories, summoned by a distinct call, may join the attack. Other birds may gather to watch as the Mockingbirds harass the intruder. This bird is mainly a permanent resident, but northern birds may move south during harsh weather. Mockingbirds have a strong preference for certain trees such as maple, sweetgum, and sycamore. They generally avoid pine trees after the other trees have grown their leaves. Also, they have a particular preference for high places, such as the topmost branches of trees. Although many species of bird imitate other birds, the Northern Mockingbird is the best known in North America for doing so. It not only imitates birds but also other animals and mechanical sounds.