Great-tailed grackles can independently direct their eyes toward different targets

Many species use eye movements to direct their overt attention toward specific targets within their environments. Some species can move each eye independently but we have a limited understanding of whether they can simultaneously monitor different targets with each eye. This study, therefore, tested whether a songbird can independently move its eyes towards two different targets. Captive great-tailed grackles (Quiscalus mexicanus) were simultaneously presented with one target in their left visual field and another target in their right visual field; the targets were both in the upper visual fields, both in the lower visual fields, or one target was in the upper visual field of one eye, while the other target was in the lower visual field of the other eye. The grackles correctly directed their left and right eyes toward the targets regardless of where the targets appeared at levels greater than chance. These results demonstrate that an avian species can perform simultaneous eye movements towards two different targets.