Mass mortality events are ever more common, putting more animals at the risk of extinction. The reasons for these mass die-offs vary, with things such as natural (e.g. disease and climate-related) and human-related (e.g. pollution) factors being common causes. Even so, many of these mass animal deaths remain a mystery to this day.
Click through the following gallery and get to know some of the most tragic—and indeed mysterious—mass animal deaths of recent times.