I've noticed that it is often "ostriches" or "ostrich" according to different sources. Does it vary by the dialect of English?
Normally I'd use Google to determine something like this, but unfortunately the search for "ostrich" plural is overcounted because of references to the singular "ostrich".
Dictionaries laying around were inconclusive. One listed plural as "ostrich" another listed "ostriches". In cases where the dictionaries disagree or where there are multiple possible solutions I tend to go with the more common answer. That is something that can be easily found by googling, but not in this case