Working with fowl tibiotarsals: insights into caponization and poultry keeping in medieval Portugal

• Cranio-caudal bending and robust shafts characterize tibiotarsi of capons and egg-laying hens. • Management strategies and breed types explain size and shape variation in fowl leg bones. • Intensification of egg-production improves the keeping of sturdier fowl morphotypes. Caponization of young male birds is a practice undertaken to fatten and improve the quality of the bird’s flesh. Ethnographic work carried out in the village of Freamunde in northern Portugal, allowed us to record in detail the traditional method used to caponize young roosters. We also obtained a small reference collection of capon bones. Since studies of modern poultry indicate that tibiotarsals may be structurally modified as a result of caponization resulting in greater body weight, we focus our attention on this bone. The shape and the size of the tibiotarsals obtained are studied to explore osteological and metrical characters that might help in the recognition of capons in archaeological remains of this taxon. The same methodological approach is applied to Portuguese medieval poultry assemblages dated to the Islamic and late medieval period. However, the observed variations in the size and the shape of the archaeological chicken tibiotarsals are hypothetically interpreted as reflecting an increased interest in egg-production in the course of time.