When millions of monarch butterflies take to the sky and fly thousands of kilometres from the United States and southern Canada to Mexico, the view is breathtaking. But over the last few decades, their numbers have plummeted, and last year hit an all-time low. Illegal logging in Mexican forests, where the monarchs hibernate during winter, has…

Gene banks are missing more than half the wild relatives of the world’s most important food crops — which potentially harbour traits for higher yields, and resistance to disease and climate change — according to a study. Scientists looked at 29 staple crops, including rice, wheat and potato, and found that around 240 of their…