One moment it was quiet and calm in the forest, the next, the air was charged with tension. The elephant had heard the distant alarm calls of animals and her mood suddenly changed. I urged the elephant deeper into the forest. We sounded like a forest fire --- cracking, snapping, trailblazing. But through all the noise came a sharp warning cry. The elephant stopped and we heard it again --- the tell-tale call of a spotted deer. I looked quickly around the shadows of the forest. Rays of sunlight shone through tree branches, beneath which the patchwork of green plants and shadows-within-shadows would make tiger stripes look more attractive. Apart from an occasional noise from the elephant's stomach, the forest was silent. Gradually, the tension slipped from our bodies. The elephant seized a nearby branch and put it into its mouth. I reached forward and gently moved my hand over the elephant's neck; there was a soft part, free of wrinkles and hairs, behind her ear. This was my fourth time _ of the forest in Corbett, although I saw no tigers in the end. Located at the foot of the Himalayan mountains, Corbett is home to about 135 Bengal tigers, but the forest seemed to be guarding their whereabouts , a silent reminder of their secrecy and rarity. Still, I was happy enough touching the elephant behind the ear. If I had so desperately wanted to see a tiger, I could have gone to a zoo. After all, spotting tigers merely confirms their beauty; tracking them can make you aware of something more. The author begins his account of the tour in the forest mainly by   _  .
describing various sounds comparing different animals listing different activities introducing various plants