hi feathers n jack,
in answer to your question you need not be worried that you have sited one,
privilaged yes, worried no...
the hoopoe is a migrating bird and they pass over here in spring from arond april to late may... , they migrate north from africa to europe, they dont however breed in this country, usually they are spotted singly and not in groups when they do arrive here, .. we can get quite a few in the south side of the country anything upto 100 to 150 birds have been spotted sometimes in groups of a couple of males , they basically coast the shore lines and cliffs after the many insects that come with the humidity and warmth our springs usally bring....
it is slightly unusual that 1 should turn up in ireland but not impossible, a waif maybe dropped out and slightly lost but once in full health will soon be in flight and to its origional post, ...
your best bet if you want more information is to contact the rspb and they can maybe give you more advice and a bit more info abot the bird itself,
hope this helps

katie