Economic Decision-Making in Parrots.

Economic decision-making involves weighing up differently beneficial alternatives to maximise payoff. This sometimes requires the ability to forego one's desire for immediate satisfaction. This ability is considered cognitively challenging because it not only requires inhibiting impulses, but also evaluating expected outcomes in order to decide whether waiting is worthwhile. We tested four parrot species in a token exchange task. The subjects were first trained to exchange three types of tokens for a food item of low, medium, and high value and successfully learned to exchange these in an order according to their value. Subsequently, they were confronted with a choice between a food item and a token that could be exchanged for higher-quality food. In additional control conditions however, choosing a token led to an equal or lower payoff. Individuals of all species were capable of deciding economically, yet only large macaws outperformed the other species in one of the crucial controls. For some individuals, particularly African grey parrots, the token apparently had an intrinsic value, which prevented them from choosing economically in some control conditions and which should be considered as potentially confounding by future token exchange studies.

Coronary and valve angiodysplasia unmasked by eosinophilic vasculitis and endomyocarditis.

A previously unreported case of a complex congenital cardiac anomaly consisting of coronary and valvular angiodysplasia, complicated by an eosinophilic endomyocardial disease, is described. The disorder presented clinically with congestive heart failure, which was characterized by evidence of floating masses causing severe pulmonary stenosis and dysfunction of the mitral and aortic valves. Symptoms of cardiac failure disappeared following pulmonary valve replacement and steroid therapy.