Network representation of cattle trade data in Brittany (Northwestern France) between dairy farms from 2009 to 2013. Diagram shows animal movement data aggregated spatially by municipality and temporally over the whole period. Size of filled circles corresponds to the number of animals (yearly average herd size) present in each municipality (represented on the map at its geographical location), and their colour to the polarity (blue when rather seller and red when rather buyer). Lines represent animal movements between municipalities (direction is neglected), and their thickness is proportional to the number of traded animals. Movements from and to outside the metapopulation are not shown.