Male budgie birds who show smarts become more attractive in the eyes of female counterparts, a new study suggests. According to the results, direct observation of "clever behavior," such as the ability to solve problems to gain access to food, can affect mate preference in birds by making particularly adept males the preferred mates of females, a behavior which could underlie the evolution of cognitive performance in non-human animals. Since first proposed by Darwin, it's long been hypothesized that more intelligent individuals make preferable partners and that sexual selection for acuity has greatly contributed to the evolutionary development of cognitive abilities in animals. However, the fitness benefits of cognition, as well as the underlying selective mechanics, are not well understood and seldom studied outside of the human species. Previous studies on birds have inferred a preference for mates with greater cognitive abilities based on secondary behaviors correlated with intelligence, like song. However, such conclusions are limited and do not directly address the role of cognitive ability on mate choice, according to the authors. Jiani Chen and colleagues tested female preference for problem-solving abilities in males, using the budgerigar - a small Australian parrot, also known as the parakeet. Chen et al. examined whether female budgerigars altered their preference for males after observing a potential suitor's ability to open puzzle boxes and access the food within. In a series of trials, female birds were paired with two males from which she chose a preferred partner. Then, outside of the view of the female, the non-preferred male was trained to open boxes of food. According to the results, after the females watched the trained bird successfully open the boxes - and observed her non-trained chosen partner fail to do the same - they shifted their preference to the previously non-preferred, clever males. Georg Striedter and Nancy Burley discuss the study, as well as its limitations in a related Perspective.