Plenty of poets wrote them, but the most famous of all is John Milton's  Lycidas . Like all typical pastoral elegies, Milton mourns the loss of his best bud (who died in a shipwreck). But he also compares him to a shepherd and describes the ways in which nature mourns his loss, too.
The Banff longnose dace, a small minnow, was recently declared extinct. It failed to compete with the guppies, swordtails, sailfin mollies and other tropical fish that had been released in the warm marsh below the famous hot springs by tourists and national park officials.
The thylacine is likely to have become near-extinct in mainland Australia about 2,000 years ago, and possibly earlier in New Guinea. The absolute extinction is attributed to competition from indigenous humans and invasive dingoes.