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 traditionally been to blame. But large-scale logging by companies appears to have been halted. And now small-scale logging by local people for firewood and timber — a “growing concern in 2013” — has also stopped, according to a study published last month (27 October) in Biological Conservation.

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 450 wild relatives need collecting and placing in gene banks. They published their findings on the Crop Wild Relatives website last week (22 July).