Not all Glossy Ibis show the blue line in fall
and winter. However, they do have a distinctive pattern of facial skin at
all seasons. The Smiths' pix are so good that they can rule out Glossy
Ibis by the absence of its distinctive facial skin pattern. Here's a link to a
photo of a Glossy on which that pattern can be made out even though the blue
line is not evident.
Here's a site on which you can see
that pattern in a variety of plumages, using internal links: