Blacktail Deer Plateau Errors in my bread

After taking a long, slow walk around the plateau, Peregrine sat down beneath the shade of an oak tree and leaned against the trunk with a happy but weary sigh. He closed his eyes and took a moment to catch his breath and relax his muscles, which were twitching subtly from the day's exertions.

When he reopened them, he started. The sky seemed dimmer. Yet when he lifted his dusky blue-green eyes, he saw no clouds and no hint of blustery weather. And still the day was gradually leeched of its color. Peregrine grew very tense, his fur prickling, as he wondered if he should rise and gather his family... but then what?