Harbour porpoises are small, shy and almost impossible to count from a boat, especially at night or in rough seas. Yet European law requires countries to know where they are and protect them.
Food companies are being asked to prove that their farms are good for nature, yet very few farms measure biodiversity at all, because hiring an ecologist is expensive.
For years, ecologists who wanted to record bats, birds or frogs in the field needed recorders costing around a thousand dollars each, which limited most studies to a handful of sites.
In a dense rainforest, a ranger standing a few hundred metres from a chainsaw may never hear it. By the time satellites spot the clearing, the trees are gone.
Before 2007, ecologists who wanted to leave a recorder in the forest had to build their own from parts, waterproof it and hope it worked.
