Two small birds share a stream, and the poem watches how differently each one lives with the water. The winter wren flies low over the current and sings a tangled, wheezing song, which the speaker compares to a hurdy-gurdy. The waterthrush does something stranger: it walks along the bottom, tail bobbing as if on a spring. The poem's one general statement, that "not all water-lovers / are bouyant in the same way," quietly tells us that loving a place can take many forms.
The ending shifts to "we," a pair or group standing "dripping in the rain." After the birds' ease and energy, the people seem a little soggy and plain, simply present and getting wet. The mood is gentle, curious, and humble. Judging by the title, "Lotic," a word for fast-moving water, the speaker is tuned in to the stream itself, and happy to stand in the weather and pay attention.