The structure that is an adaptation to help break down food is the gizzard which consist of strong muscle to help break down and digest food. it is located in lower stomach of birds and contains ingested stones to help in digestion.
The accumulation of several mutations in the main gene on the virus's surface may be able to give H7N9 the ability to spread like human flu viruses do, passing from person to person through coughing and sneezing.
