Owen, I don't believe I have ever gotten such a rude response on this forum.
The book which I have at hand reads as follows:

"In Donegal there is a song which was traditionally sung to those who were going overseas, and there is a legend in that same county that the many seagulls wheeling over the shore are the souls of Irish emigrants, returned at last to their homeland." – Valley Irish, pg. 4, Carol Bennett, juniper books, 1983, Renfrew, Ontario

I would assume that this song is likely in the Irish, and is obviously not a new composition.