Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Birds 5.85): Merillions are birds, as he says [i.e. Liber rerum], as they are commonly called. For they are not much different in shape or color from blackbirds, except that they have different feet, claws, and beaks. They are avid prey for birds, and because they are small and of little strength, they are not chasers of small birds. For they fly socially, like harriers or hawks, and four of them are able to seize the swan in this way: the first of them seizes the swan's head, the second and third the two wings on each side, and the fourth invades the breast or neck, so that the enclosed bird, surrounded by constrictions, cannot move. Not being able to escape the swan is captured and killed. - [Badke translation/paraphrase]