Research suggests that half of the world's wildlife  have been eliminated in the last forty years. The news must be a dark cloud over almost anyone with a capacity for wonder .
I find myself turning to Aldo Leopold (1949):
This song of the waters is audible to every ear, but there is other music in these hills, by no means audible to all. To hear even a few notes of it you must first live here for a long time, and you must know the speech of hills and rivers. Then on a still night, when the campfire is low and the Pleiades have climbed over rimrocks, sit quietly and listen for a wolf to howl, and think hard of everything you have seen and tried to understand. Then you may hear it—a vast pulsing harmony—its score inscribed on a thousand hills, its notes the lives and deaths of plants and animals, its rhythms spanning the seconds and the centuries.
 (Added 14 October 2014) The 11 October 2014 edition of More or Less on the BBC World Service unpacks the detail behind that headline, and slightly misleading, figure.
Image: rear end of Soviet jet train via EnglishRussia. Update 3 Oct: See also the work of Cai Guo-Qiang.