In just five short lines, this poem turns nightfall into something an owl swallows. Night doesn't simply arrive; it drops "into an ear of owl," as if the owl's hearing is where darkness begins. That fits what we know of owls, which hunt by sound as much as sight, so the dark here is almost something heard.
The word "ecclesiastical" gives the night a churchlike hush, as though dusk were a ritual or a service. Then the ending shifts the tone: night falls "with great pain and love / for his supper." The owl's meal means death for some small creature, and the poem holds tenderness and cruelty together in one breath. The speaker doesn't judge. Instead they watch, with a calm kind of awe, and the mood is quiet, solemn and a little eerie. Hunting becomes something sacred, and love and pain seem like two sides of the same night.