Flying birds went pattering; running beasts were fierce and wild.

The poem changes gear from five characters a clause to four, and it will keep changing. 淅瀝 is a sound word — the patter of rain, of leaves, of wings — and pairing it against 兇頑 sets a small noise beside a large menace.

Within the wood a thousand pine trunks; over the ridge a few stems of bamboo.

A thousand against a few, and the two counting words are chosen to match the plants — 榦 for a tree trunk, 竿 for a bamboo pole. The line is a small display of getting the measure words right.

That roaring is grey wolves seizing their kill; that snarling is starved tigers fighting over a meal.

哮 is xiào, the falling reading — 咆哮 is the noise a big animal makes when it is angry, and modern Chinese still uses it of rivers and of people. The two clauses are built identically, sound first and cause second, so the mountain is described by what you would hear before what you would see.

Wild apes give long howls as they hunt for fresh fruit; elk climb through the flowers into the blue-green haze.

長 is cháng, long — the howl is drawn out, and this is not the zhǎng of growing or of seniority. 翠嵐 is the blue-green vapour that hangs on wooded mountains, a word that exists mainly for painting and poetry. Note who is here: apes, on a mountain, in the chapter whose title calls Pilgrim the Mind-Ape.

The wind scatters and scatters, the water runs and runs, and now and then a hidden bird is heard calling in its own broken speech.

Three clauses of three, three and seven — the poem breaking its own stride. 灑灑 and 潺潺 are both doubled sound words, and 間關 is a third, made for birdsong specifically: the stopping and starting of it.