The changes in condition between birds before and after flight are evident in these two Great Knots. The bird on the left was collected soon before migration from Northwest Australia. The bird on the right was collected immediately upon arrival in China, 5,400 km away. Note the thick layer of fat underlying the skin and within the abdomen of the premigration bird, and the shrunken flight muscle of the birds on the right (the true left pectoralis of each bird has been removed).