The reasoning made by the scientist after observing the behavior and activity of the chimps is known as inductive reasoning.
The inductive reasoning is said to be made when the generalizations are made based on the specific behaviors of the subjects. In the given experiment, the scientist observes the behavior of the chimps, who are putting dry leaves in the tree hole, which makes the leaves wet and then they lick water. Based on this it can be broadly concluded that the water is coming from inside the trees.
Hence, the answer is 'inductive reasoning'.