8 out of 14 (Rhinos)

It is deeply disturbing that 8 out of the 14 endangered Black rhinoceros that were moved (for their protection) to a national reserve in southern Kenya have promptly died (https://www.theguardian.com/world/2018/jul/13/kenya-rhinos-die-after-being-moved-between-national-parks). It is suspected that salt poisoning is the root cause as the waters in the reserve are notably more salty. This kind of disaster shows how conservation can be imperilled by small issues.