The speaker has accidentally startled some water birds on a remote lake, and instead of just moving on, he stops to ask why they flee. He immediately understands: they see a human, and to them, the human is a tyrant who kills for sport, not out of necessity like a hawk. There’s a real pang of shame here. He sees himself through their eyes: just another dangerous human, the “proud, usurping foe” who claims to rule nature. This makes him blush for the whole human race, because we boast of pity but kill for fun.
The mood is gentle, sad, and admiring. These birds live a self-contained life on a hidden lake, depending on nothing but nature. Their peace is perfect until a human appears. And when we do, they don’t cower—they flee with a scornful clang of wings, seeking other springs. The speaker seems to envy that defiance, even as he mourns his own species’ cruelty. There’s a quiet fury beneath the tender address, a recognition that our power is real but our morality is broken.