I have the 2015 calendar from the Jewish Historical Museum in Amsterdam, and today I noticed that the September page has a picture of a shofar made from an ibex horn. The calendar dates it to 1850-1900 (Amsterdam) and has the catalog number JHM00837.
Coincidentally, this week's edition of my local Jewish newspaper contains an article about somebody researching the history of the Jewish community in southern Italy (Calabria), and there too there is mention of blowing an ibex-horn shofar.
These are the only two times I've heard of an ibex horn being used for a shofar instead of the usual ram's horn, and in one case we only have an anecdote in the press. So I'm wondering: is or was an ibex horn commonly used anywhere? (If so, where and when?) Or would that be giving too much weight to a single Dutch artifact and some Italian stories?
I know that some of the Jews expelled from Spain in 1492 ended up in various parts of Italy and some ended up in Amsterdam. So if using an ibex horn was done in both places, there could have been a common origin.
This question talks about Yemenite Jews using an antelope (not ibex) horn because, according to the answer, they find it more beautiful than the Rambam-mandated ram's horn. An ibex is not an antelope and I'm not aware of commonalities among these communities, but I mention it in case it's relevant.