here's the lawyer in me rearing her ugly head and getting into technicalities - ostrich does come with documentation, but it's a certificate of origin rather than a CITES certificate.
a CITES certificate is documentation that an article (or specimen) of a species subject to the CITES treaty was harvested in conformity with the treaty rules. farmed ostrich is not a species subject to the CITES treaty, and it is not possible to get such a certificate. what you get is a certificate of origin - which demonstrates that the ostrich in question is not one of the wild species that IS subject to the treaty (and would therefor require a CITES certificate).
which is the long way of saying, with ostrich what you get is a document that shows that you don't need the CITES.