The bird remains are characterised by a high frequency of unidentifiable fragments (table 5). Bones from geese are rather frequent and probably belong almost exclusively to the domestic goose (Anser anser f. domestica). Remains from ducks are less common and possibly all represent the domestic duck (Anas platyrhynchos f. domestica). Domestic fowl (Gallus gallus f. domestica) is the most abundant species, mostly represented by adult animals. Other bird remains include a partial skeleton of a sparrowhawk (Accipiter nisus), and a number of bones from little owl(Athene noctua) and domestic pigeon (Columba livia f. domestica). Whether the latter three species represent food remains, is unclear. These animals were possibly simply killed when coming near to the tower, or were found dead and cleaned away.
Domestic pigeons were, however, only introduced into the Low Countries during the late Middle Ages, to be kept as a status symbol (but also manure producers) in towers near castles or abbeys. Soon, they escaped and started to breed on high buildings in towns (Benecke 1994). The status of the pigeon remains is thus unclear: they could represent a food item brought in from some richer household, or a feral animal living on or around the tower. The spectrum of bird remains is completed by a number of songbird bones (Passeriformes sp.), unidentified eggshell fragments, tracheal ‘rings’ (bone elements supporting the trachea) and small, polished stones, known as ‘gastroliths’, swallowed by birds and used as grinding material in their digestive system (fig. 22). All skeletal elements are represented, except, in the most commonly found species, the bones from the tips of the wings.