In New Scientist magazine, I read this cute mini-article:

Penguins are not visible from space, but their faeces are. British Antarctic Survey scientists have used satellite images to locate the reddish-brown guano stains of emperor penguin colonies. The work will allow the team to monitor the penguins’ response to climate change”

Good old scientists! 🙂

(New Scientist, 6 June 2009, p7)