Predation of vertebrates by Mallards (Anas platyrhynchos) has rarely been documented and only in relation to fish and amphibians. Mallard foraging behavior was observed at a reservoir bordering Semenic-Caras Gorges National Park in southwest Romania. A group of Mallards comprising one adult female and 10 subadults was recorded hunting, killing and consuming hatching year passerine birds of two species, a Grey Wagtail (Motacilla cinerea) and a Black Redstart (Phoenicuros ochruros). These are the first records of hunting of birds by wild Mallards. This extraordinary new behavior represents substantial diet expansion for this widespread and abundant duck species.