McCormick’s Skua - Feet
1. Nestling, right after hatching
2. Nestling, two to three weeks old
3. Juvenile, around the time of downy feather shedding
4. Normal adult
5. Piebald morph of adult - Juvenile coloring retained, with adult feathering
National Antarctic Expedition 1901-1904: Natural History - Vol II. Zoology. The Order of Trustees of the British Museum, 1907.