Kumlien's Iceland Gull
in third (winter) basic plumage. Third year birds are the rarest age
class in the population. Later this year in the fall this individual
will become an adult. Adults and first year birds are the two
commonest age class in the population, followed by second year
birds, and finally third year birds such as this individual, which
are the least common age class as mortality accumulates before adult
plumage is reached. 18 February 2008.