Here I report a feeding innovation by Shiny Cowbirds (Molothrus bonariensis) in which the birds feed on the nectar of flax (Phormium tenax) flowers. Flax frequently is cultivated in Mar del Plata City, Buenos Aires Province, Argentina, as an ornamental plant, and the Shiny Cowbird is common there. The length of the cowbird's bill is similar to that of the flax flower tube, which permits the cowbird to access the nectar. Further, the panicle stem of the flax is sufficiently rigid for perching, and the short distance between the stem and the flower enables a perched cowbird to reach the flower. At this site, flax nectar probably is utilized in a sustainable manner, as the flowers apparently are not harmed. Future investigations should examine whether or not the observed behavior is restricted to this particular population and if it is not, determine the spatial and temporal extent to which it occurs.