If the silence up at the Nixon Fork gold mine in Southern Alaska seems slightly eerie, then at least there's nothing sinister about it. It's not the calm before the storm, even if the Alaskan winters do come early, and the clouds are already rolling in grey and low as August draws to a close. It's not even a lurking sense of menace at the hidden, but well-attested presence of bears in the woods nearby. No, the silence, and its associated eeriness derive from two distinctly separate, but benign factors. One: despite Nixon Fork's setting at the centre of hundreds of square kilometres of mountainous and wooded Alaskan wilderness, there are no birds in the trees.