According to a global study, snakes may be declining across the world. Researchers examined records for 17 snake populations covering eight species over the last few decades, and found most had declined markedly. For reasons that are not entirely clear, some populations shrank in number abruptly around 1998. Species in decline include the asp and the smooth snake from Europe, the Gabon viper and rhinoceros viper of West Africa, and the royal python.Writing in the journal Biology Letters, the researchers describe the findings as "alarming" but say much more work is needed to understand the causes. Dr Reading's team at the UK's Centre for Ecology and Hydrology ran the study with institutions in Australia, France, Italy and Nigeria.