Training is one of many tools that an animal care staff uses to enhance the welfare of the animals under their care. Historically, animals have been trained to shift on and off exhibit, providing opportunities to examine them closely, offer individual diets, and create an environment that facilitates enhanced care. By training this and other behaviors, the number of physical captures and handlings can be minimized, reducing safety hazards to both animals and caretakers. Animals can be trained to participate voluntarily in their own medical care. Additionally, training can facilitate research on zoo and aquarium animals; results from these studies can enhance our abilities to understand and care for animals. Presumably, training provides a level of cognitive stimulation for animals (Hediger 1950) and thus may be enriching to the animals as well.