Abehavioral psychologist tries to train a bird to climb a tree to get a reward of a piece of fruit. at first, the bird learns how to climb the tree with its legs and beak. after a while, it starts flapping its wings and hopping around before it starts to climb. eventually, the bird flies up to the piece of fruit, even though the use of its wings prevents it from being reinforced with the fruit. according to the brelands' analysis of biological constraints, the bird is demonstrating