How does Buck behave at the camp chapter 7

When Buck enters camp in Chapter Seven, he overwhelms John Thornton, so happy is he to see him. For two days he does not leave the camp or let John Thornton out of his sight. Then he once again becomes restless. Buck sleeps away from the camp, wandering the forest and searching for his wolf brother for days a time. He kills a black bear in a vicious fight, and when he returns to the kill and sees a pack of wolverines, he kills two of them as well. The urge to hunt and kill grows stronger in him.

Sometimes he pursued the call into the forest, looking for it as though it were a tangible thing, barking softly or defiantly, as the mood might dictate. He would thrust his nose into the cool wood moss, or into the black soil where long grasses grew, and snort with joy at the fat earth smells; or he would crouch for hours, as if in concealment, behind fungus-covered trunks of fallen trees, wide-eyed and wide-eared to all that moved and sounded about him. It might be, lying thus, that he hoped to surprise this call he could not understand. But he did not know why he did these various things. He was impelled to do them, and did not reason about them at all.

Irresistible impulses seized him. He would be lying in camp, dozing lazily in the heat of the day, when suddenly his head would lift and his ears cock up, intent and listening, and he would spring to his feet and dash away, and on and on, for hours, through the forest aisles and across the open spaces where the niggerheads bunched. He loved to run down dry watercourses, and to creep and spy upon the bird life in the woods. For a day at a time he would lie in the underbrush where he could watch the partridges drumming and strutting up and down. But especially he loved to run in the dim twilight of the summer midnights, listening to the subdued and sleepy murmurs of the forest, reading signs and sounds as man may read a book, and seeking for the mysterious something that called—called, waking or sleeping, at all times, for him to come.

One night he sprang from sleep with a start, eager-eyed, nostrils quivering and scenting, his mane bristling in recurrent waves. From the forest came the call (or one note of it, for the call was many noted), distinct and definite as never before,—a long-drawn howl, like, yet unlike, any noise made by husky dog. And he knew it, in the old familiar way, as a sound heard before. He sprang through the sleeping camp and in swift silence dashed through the woods. As he drew closer to the cry he went more slowly, with caution in every movement, till he came to an open place among the trees, and looking out saw, erect on haunches, with nose pointed to the sky, a long, lean, timber wolf.