ocr: - - for WildTigers By GEOFFREY C. WARD Photographs by MICHAEL NICHOLS NATIONAL GEOGRAPHIC PHOTOGRAPHER, Resting after a night ofbunting, a tigress called Sita remains a sentinel, ready to leap at thethroat ofany creature that dares approach the den where her cubs liel hidden in India's Bandhavgarh National Park. Alarm- ingidrops int world diger-populations presentai quandary; howto preserve wildi cats in wild lands asfarmsand cities eataway: at habitatand. poach- ersstep up their murderous.trade.