Hisham bin Urwah (may Allah have mercy on him) narrates from his father (may Allah have mercy on him): For a wild cow, a cow; and for a wild goat and a gazelle, a goat. Imam Malik (may Allah have mercy on him) says: I have always heard that when a muhrim kills an ostrich, the sacrifice of a camel is due for it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9871