Adult | |||
 | white quills on outer primaries forming white panel | ||
 | narrow bill yellowish brown tip | ||
 | gray toes covered with chalky excrement | ||
 | gray skin on featherless head wrinkled neck | ||
Juvenile | | ||
 | black skin on head black tip on mandibles (changes to yellowish brown) | ||
 | duller black than adults | ||
Nestling | |||
 | Buff colored long, thick, black beak |