A tool-using performance in an animal or bird is specified as the use of an external object as a functional extension of mouth or beak, hand or claw, in the attainment of an immediate goal. This goal may be related to the obtaining of food, care of the body, or repulsion of a predator, intruder. If the object is used successfully, then the animal achieves a goal in which a number of instances would not have been possible without the aid of the tool. A variety of birds show behavior closely related to tool-using. Some of the purposes include: (1) use of thorn or twig as a “skewer”, (2) use of spine or twig as a probe, (3) use of the bark “plug”, and (4) use of stones and rocks. Tool-using and related behavior in mammals and in primates is also reviewed. Tool-using behavior in primates falls into two distinct categories: the use of objects as weapons in aggressive contexts; and in non-agonistic contexts for obtaining food for investigation and body care.